Blackstone Ahi Tuna (Seared Tuna on the Flat Top)

Seared ahi tuna is one of the best things to cook on a Blackstone griddle. The technique is simple: extremely high heat, a sesame or pepper crust, 60–90 seconds per side, and you’re done. The Blackstone’s large steel surface gets hotter than most home stovetops and sears the tuna instantly while leaving the center raw to rare — exactly where sashimi-grade tuna should be.

Use sushi-grade or sashimi-grade tuna. This is not a dish where the grade of fish doesn’t matter.

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Ingredients

For the tuna:

• 2 ahi tuna steaks (6–8 oz each, at least 1 inch thick), sushi-grade
• 2 tbsp avocado oil (high smoke point)
• ¼ cup sesame seeds (white, black, or mixed)
• 1 tsp coarse salt
• 1 tsp cracked black pepper
• Optional: 1 tsp wasabi powder mixed into the crust

Dipping sauce:

• 3 tbsp soy sauce or tamari
• 1 tbsp sesame oil
• 1 tbsp rice vinegar
• 1 tsp ginger, grated
• 1 tsp honey
• 1 green onion, sliced thin
• Pinch of red pepper flakes

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Instructions

Step 1: Make the dipping sauce

Whisk together soy sauce, sesame oil, rice vinegar, ginger, honey, and green onion. Set aside.

Step 2: Prep the tuna

Pat tuna steaks completely dry with paper towels — moisture prevents searing. Brush lightly with avocado oil. Press sesame seeds, salt, and pepper firmly onto all four sides of each steak.

Step 3: Get the griddle scorching hot

Crank the Blackstone to maximum heat. Let it preheat 5–7 minutes until the surface exceeds 450°F. This is a restaurant-quality sear that requires restaurant-level heat.

Step 4: Sear — 60–90 seconds per side

Add a thin film of avocado oil to the hottest zone. Place the tuna steaks down and do not touch them. Sear for 60–90 seconds — you’ll see a white line of cooked tuna creeping up the sides. Flip. Sear 60–90 seconds on the second side.

Step 5: Sear the edges

Stand the tuna on each narrow edge for 15–20 seconds to sear. This seals the crust all the way around.

Step 6: Rest briefly and slice

Rest for 1–2 minutes. Slice against the grain into ½-inch medallions. The center should be ruby red to deep pink — raw to rare. Serve immediately with the dipping sauce.

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Tips

Maximum heat only. Ahi tuna searing is a race against time — the crust needs to form before the interior heats above rare. Lower temperatures cook the center through before the sesame crust sets. Don’t try this at medium heat.

Sushi-grade fish. Only sushi-grade or sashimi-grade ahi tuna is appropriate for a rare center. Ask your fishmonger specifically for sashimi-grade yellowfin or bigeye tuna.

Dry the fish. Any moisture on the surface creates steam that prevents searing. Paper towels, then pat again. The surface should look matte, not shiny.

Don’t move it. The sesame crust sticks to the griddle for the first 20–30 seconds as it sears. It will release naturally once the crust sets — don’t force it.

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Variations

Peppercorn-crusted ahi. Swap the sesame crust for coarsely cracked black peppercorns pressed into all sides — the steakhouse treatment. Same 60–90 second sear; the pepper toasts against the steel and forms a crust with real bite.

Spicy mayo drizzle. Slice the rested tuna, fan it over rice, and drizzle with spicy mayo — the two-minute sauce that turns seared ahi into a restaurant-style tuna bowl.

Poke-style bowl. Sear as written, rest, then cube instead of slicing into medallions. Toss the cubes gently with a spoonful of the dipping sauce and serve over rice with cucumber, avocado, and green onion — seared-edge poke, no raw-prep knife work required.

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Buying Ahi Tuna (This Part Matters)

Because the center stays raw to rare, the grade of the fish is a food-safety decision, not a quality preference. Buy tuna explicitly labeled sushi-grade or sashimi-grade — the label indicates fish handled and deep-frozen to the standards for raw consumption. The vacuum-sealed frozen sashimi-grade steaks at well-stocked grocers are a reliable choice; thaw overnight in the refrigerator. A regular “ahi steak” from the seafood counter without that labeling should be cooked through instead — at which point a different fish (like mahi) honestly makes a better dinner. Look for steaks at least 1 inch thick, deep pink-red, with no browning at the edges.

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What to Serve With It

Seared ahi is rich and clean at once — keep the plate in that lane: steamed rice, quick-pickled or smashed cucumbers, edamame, or a seaweed salad. Off the same griddle, asparagus seared hard in the residual heat is the best hot side that won’t compete with the dipping sauce.

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Storage

Seared-rare tuna is a serve-immediately dish. If you have leftovers, refrigerate them tightly wrapped and eat within 24 hours — cold, sliced thin over a salad or rice, never reheated. Reheating cooks the rare center you built the whole dish around and turns premium tuna into canned-tuna texture.

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More flat-top recipes: Blackstone Fish Recipes · Blackstone Dinner Ideas · Blackstone Asian Recipes

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Frequently Asked Questions

What temperature do you cook ahi tuna on a Blackstone griddle?

450–500°F — the hottest your griddle will go. Ahi tuna is seared for only 60–90 seconds per side and served rare in the center. Maximum heat is essential for developing a seared crust before the interior heats above rare.

How long do you cook ahi tuna on a Blackstone?

60–90 seconds per side — 3–4 minutes maximum. Ahi tuna is intentionally served rare in the center. If you want well-done tuna, cook 2–3 minutes per side, but the texture and flavor will be significantly inferior to rare.

How do you know when seared ahi tuna is done?

Watch the sides — you’ll see a white cooked line creeping up from the bottom as you sear. For rare: the white line should extend about ¼ inch up from each side. The center should remain ruby red when sliced. At 90 seconds per side on maximum heat, this is typically achieved.

Can you use frozen ahi tuna for searing?

Yes, if it was frozen properly (sashimi-grade fish is often flash-frozen at sea). Thaw completely in the refrigerator overnight, pat very dry, and bring to room temperature for 20 minutes before searing.