Sesame Mustard Tuna: Pan-Seared and Rare

Making Bold Sesame Mustard Tuna

A loud hiss and the smell of toasting seeds hit the air the second the fish touches the pan. That's the sound of a win. For a long time, my home attempts at seared tuna were a disaster, usually resulting in a grey, rubbery block or a crust that slid off like wet pebbles.

I used to try soy based marinades, but they made the tuna surface too slippery for the seeds to stick. Once I swapped the soy for a thin layer of mustard, everything changed. The seeds actually stayed put, and the sharp tang of the mustard cut through the richness of the fish.

This Sesame Mustard Tuna is for when you want high impact flavor without spending an hour in the kitchen. You get a mahogany colored edge and a center that stays bright red and cool. It's a fast, fusion style meal that feels expensive but takes almost no effort.

Why The Crust Stays

The Mustard Bridge: Dijon mustard acts as a tacky adhesive. It creates a bond between the fish and the seeds so they don't scatter in the oil.

Over High heat Flash: A screaming hot pan browns the seeds in seconds. This prevents the heat from penetrating too deep into the tuna, keeping the center rare.

Essential Flavor Components

Most people overcomplicate the coating, but the goal here is contrast. The mustard isn't meant to be a dominant sauce, but a bridge. It adds a hit of acidity that balances the fatty tuna.

Using both black and white sesame seeds isn't just for looks, as they toast at slightly different rates and offer a more complex nuttiness.

For the tuna, you need sushi grade Ahi. Since we are searing it for less than a minute per side, the quality and safety of the raw fish are everything. USDA guidance puts the safe internal temperature for fish at 145°F, but for this specific style, we aim for a rare center.

Required Kitchen Gear

A cast iron skillet is the best choice here because it holds heat better than stainless steel. If the pan temperature drops when the fish hits, you'll get steaming instead of searing. You also need a sharp chef's knife for the final slice, as a dull blade will tear the fish and ruin the clean look of the medallions.

Chef's Note: Use avocado oil instead of olive oil. Avocado oil has a much higher smoke point, so it won't burn or taste bitter when you crank the heat to high.

Cooking The Fish

1. Dry the tuna steaks thoroughly using paper towels. Note: surface moisture creates steam, which prevents a crisp crust.
2. Lightly season the fish with 1/2 tsp kosher salt and 1/4 tsp black pepper.
3. Apply a thin, uniform coating of 2 tbsp Dijon mustard to all sides of the steaks.
4. Combine 2 tbsp white sesame seeds and 2 tbsp black sesame seeds on a flat plate.
5. Press the mustard coated tuna into the seeds, pushing down firmly to ensure the fish is fully encrusted.
6. Place a cast iron skillet over high heat and warm 2 tbsp avocado oil until the oil shimmers and almost smokes.
7. Add the tuna to the pan and sear for exactly 45-60 seconds per side.
8. Remove the fish immediately once the seeds are deep golden brown and a thin cooked band forms.
9. Let the steaks rest on a cutting board for 3 minutes to allow the juices to settle.
10. Using a sharp knife, slice against the grain into 1/2 inch thick medallions.

Fixing Searing Problems

A crust that won't stick is usually the result of excess moisture on the fish or an overly thin coat of mustard. You want the mustard to feel tacky not a heavy sauce to ensure the seeds adhere properly.

A grey center indicates the temperature was too low or the fish stayed in the pan too long. Searing should be a rapid process. If you're concerned about the center being raw, keep in mind that intense heat creates a thermal gradient, searing the exterior while keeping the interior fresh.

Seed Adhesion Issues

If you lose seeds, review how you dried the tuna. Surface water prevents the mustard from bonding to the fish.

Overcooked Centers

Resist the urge to poke or press the tuna to check for doneness. Stick to the timer.

Burnt Crust

This occurs when the oil smokes excessively or the pan heat is inconsistent.

Changing The Volume

Adjusting the yield of this dish is simple. To make a smaller amount, simply cut the ingredients in half and opt for a narrower pan to ensure the oil stays concentrated. When preparing for more people, sear the tuna in stages.

Overfilling the pan causes the heat to drop, which results in the fish steaming in its own liquid rather than getting a proper sear.

When scaling up, avoid doubling the salt and pepper; instead, begin with 1.5 times the amount and taste a small bit first. Any remaining seared tuna can be thinly sliced and served atop an Ahi Tuna Bowl for an easy midday meal.

Storage and Leftovers

Seared tuna is best eaten immediately. However, you can keep it in a sealed glass jar in the cooler for up to 2 days. Don't freeze it after searing, as the texture will become mealy and the crust will get soggy.

If you have extra raw tuna that you didn't use for this recipe, consider making a Tuna Tartare instead. For zero waste, save any leftover sesame seeds in a cool, dark pantry to keep them from going rancid.

Serving Suggestions

The way you plate this dish changes the whole vibe. For a "Bistro" look, slice the tuna into medallions and fan them across a slate board. Drizzle a bit of soy ginger glaze around the edges and garnish with microgreens.

If you want something more filling, go for the "Power Bowl." Put a scoop of quinoa or brown rice in a bowl, add sliced avocado, shredded carrots, and edamame, then place your Sesame Mustard Tuna on top. The nutty crust of the fish pairs beautifully with the creamy avocado.

Right then, you've got a high end meal ready in under 15 minutes. Just remember: high heat, fast sear, and a sharp knife. Enjoy your Sesame Mustard Tuna!