Readers ask: How to cook frozen unagi?

How to Cook Frozen Unagi: A Comprehensive Guide

Unagi, or freshwater eel, is a popular ingredient in Japanese cuisine. It is known for its rich, buttery taste and tender texture. While fresh unagi is preferred in restaurants, many home cooks rely on frozen eel due to availability and cost.

If you have never cooked with frozen unagi before, don’t worry! This guide will teach you everything you need to know about preparing and cooking this delicious ingredient.


Unagi has been a staple of traditional Japanese cuisine for centuries. It’s often served as a sushi or sashimi topping, grilled with sauce glaze, steamed with broth or pan-fried crispy. The popularity and demand for unagi make it difficult to secure fresh deliveries year-round. Henceforth, many households tend to use the frozen version instead.

Of course, frozen unagi differs from fresh ones in terms of texture and shelf-life duration. But that does not imply it cannot be prepared as delicious as the fresh fish itself.

Preparing Frozen Unagi for Cooking

Before cooking your unagi, it needs to be thawed properly. You have several options when it comes to thawing methods:

  • Microwave method: Place the frozen unagi in a microwave-safe dish and defrost on low power.
  • Fridge method: Thaw overnight by placing the sealed package of frozen eel pieces inside the fridge’s main compartment.
  • Quick water bath method: Submerge the vacuum-sealed eel packs into tap water about 20 minutes before draining them out from the water’s cold temperature flow.

Once your unagi is fully thawed, you’ll want to debone and fillet it thoroughly using medium-sized kitchen scissors.

Grilling Frozen Unagi

Grilled unagi has a luscious smoky flavor when done correctly. To cook your frozen eel on a grill, you’ll need a few materials:

  • Charcoal or Gas Grill: Start by lighting up your charcoal grill ahead of the time or preheating your gas grill.
  • Aluminium foil: Line the grilling rack with aluminium foil to prevent sticking and avoid tearing.
  • Sauce brush: Use this to apply the eel’s savory sauce throughout the cooking process effectively.

Here’s how you can cook your frozen unagi on a grill:

  1. Preheat your grill to medium-high heat (if using charcoal aim for two white-hot coal piles at 300 – 350°F)
  2. Remove the vacuum-sealed package from defrosted unagi and rinse it under cold water then pat drywith paper towels.
  3. Place the cut fillets skin-down onto an aluminum-lined plate before brushing on the tare (unagi sauce glaze), coating it over each eel piece generously.
  4. Once your charcoal is ready or your gas grill has reached its optimal temperature, place unagi fillets over grilling racks and grill for six to eight minutes or more until its inner flesh hits between 140 – 165°F degrees range.
  5. Then proceed to flip each piece with a spatula before applying another layer of glaze.
  6. After allowing it to cook for an additional five minutes, remove unagi pieces from heat promptly before transferring contents onto plates.

Tips: Keep in mind that certain recipes may have different measurements and nuances of preparation. It’s always best to adjust seasoning according to preferences while also paying attention to details such as moisture level regulation let alone avoiding cross-contamination throughout each step

Pan-frying Frozen Unagi

Pan-frying is another method for cooking frozen unagi if grilling isn’t available due to various reasons; one key feature about pan frying, however, is its ability to produce crispy brown skin alongside moist flesh underneath in an instant.

To pan-fry frozen unagi, you’ll need the following equipment.

  • Saucepan: Have a saucepan that can accommodate a portion of eel fillet and hold all of eel sauce glaze, similar to what Japanese households use for home cooking of unagi dishes.
  • Cooking oil: Vegetable or canola oil is recommended since those oils have neutral flavors and high smoke points that won’t overpower the sauce’ sweetness
  • Cornstarch: This ingredient is optional to help crisp the fish’s skin while also preventing sticking on the pan.

Now follow steps below:

  1. After thawing your frozen unagi thoroughly, cut it into appropriately sized cubes or specific serving sizes based on your preference before patting it dry with paper towels.
  2. Dust both sides of each fillet with cornstarch as well as applying a layer of tare (unagi sauce glaze).
  3. Then heat up around two tablespoons of vegetable oil in a frying pan over medium-high temperature.
  4. Sear each piece for around six minutes until golden browned before flipping them over and repeating the process with the new side-cook time three minutes longer at least.
  5. Once cooked throughly, remove eel bits from the pan using a slotted spatula before transferring them onto plates.

Steaming Frozen Unagi

Steamed unagi is a nutritious way to cook frozen eel without adding too much fat compared to other cooking methods like grilling or frying. To steam your frozen unagi properly, you will need:

  • Steamer Basket: A bamboo steamer basket or metal steaming basket would work best for this method.
  • Pot: Your choice pot should be large enough to accommodate the steam rack plus extra space underneath; ideal if you have an inch gap between water level and base of rack after placing it in (for effective boiling).
  • Aromatics: The steam will infuse the eel with the aromatics’ fragrance, adding more depth to its flavor profile.

Now it’s time to prepare your steamed unagi below:

  1. Start by creating a condiment mix using either mirin or sake mixed with soy sauce and sugar.
  2. Set up the steamer’s rack on top of the pot filled with water before placing herbs (like thinly chopped ginger, garlic, white onion slices ) and cover them over and let reach boil.
  3. Cut unagi fillets into specific serving sizes or whole pieces to fit within the steamer baskets that you’re using.
  4. Brush each piece with tare followed by transferring them onto baskets/trays lined with parchment paper.
  5. Once water reaches boiling point, place the baskets on top of rack and quickly secure lid in place
  6. Steam for around 15-18 minutes until it appears opaque while maintaining moistness; thus prevent overshrinking from dehydration when you remove them out of steamers.

Baking Frozen Unagi

Baking may not be as traditional as other methods for cooking eel compared to grilling or pan-frying. However, it does give its unique characteristics whereby one can’t resist wanting more after taking a bite.

To bake frozen unagi at home:

  1. Preheat oven at 400°F. Adjust your oven temperature based on how much you prefer an authentic smoky flavor for your dish.
  2. While waiting for your preheated oven to reach optimal heat range – mix marinade ingredients together such as soy sauce (3 tbsp), brown sugar (2tbsp ), mirin (1 tbsp), salt grain , black pepper , white wine (2oz)
  3. Put thawed eel fillets inside marinade and let rest for about 30 minutes
  4. Line baking sheet with parchment paper then arrange marinated eel fillets side-by-side according to sizes preferred.
  5. Brush another layer of marinade over each fillet before putting them into preheated oven for ten minutes or until internal temperature range hits around 140-150°F.

Serving Suggestions

Traditional Japanese cuisine often includes various dishes complementing unagi-related meals. Henceforth, Here are some popular side dish recommendations:

  • Kinshi Tamago: This sweet egg garnished with chopped scallions is a staple side dish in Japan serving as a perfect accompaniment to Unagi Don (unagi rice bowl).
  • Takuan: A mildly sweet pickled yellow radish that balances the eel’s saltiness and sweetness- recommended often as siding too alongside green tea more notably during the summer season.
  • Edamame beans: As an appetizer or light snack, edamame beans boiled in saltwater till tender are considered a significant staple dish in Japanese cuisine.

There tend to be even more possibilities based on individual tastes and preferences when it comes to meal pairing; however, these three dishes will provide you with a good general statement of what one can try.


Cooking frozen unagi at home is easier than you think: Just remember to thaw it properly beforehand, adjust seasoning ingredients until satisfied, and cook it through by following thorough step-by-step instructions. Each cooking method has its benefits in creating unique textures and flavors like grill producing smokiness pan-frying gives golden crunchy coating while steaming keeps nutritional quality intact, thus giving customers diverse opinions.

By following this comprehensive guide above, one can achieve restaurant-quality results from the comfort of your own kitchen!


  • Q: Can I cook frozen unagi straight from the freezer? A: It is not recommended to cook frozen unagi straight from the freezer. You should thaw it first for best results.
  • Q: How do I thaw frozen unagi before cooking it? A: The easiest way to thaw frozen unagi is by leaving it in the refrigerator overnight. If you need to thaw it quickly, place the unopened packet of frozen unagi in a bowl of cold water and let it sit until thawed.
  • Q: What’s the best way to cook thawed unagi? A: Grilling or broiling are some of the best ways to cook thawed unagi. You can also sauté it with your favorite seasoning or bake it in the oven with some teriyaki sauce.
  • Q: How long does cooked unagi last in the fridge? A: Cooked unagi can last up to 3-4 days in the fridge if stored properly in an airtight container. It’s important not to keep cooked unagi at room temperature or reheat it more than once.

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