Step 1

Combine vinegar, water, sugar, salt, and chili flakes in a medium saucepan and bring to a boil over high heat.

Step 2

Remove from heat. Add cucumber slices and stir.

Step 3

Let it rest for 10 minutes, then transfer cucumber to a sealable container and refrigerate until ready to use.

Step 4

Whisk together all soy ginger lime sauce ingredients together in a small bowl. Set aside until ready to serve.

Step 5

Place sesame seeds on a plate. Pat dry the tuna steaks with a paper towel to remove excess water.

Step 6

Dredge and press tuna in sesame seeds, coating evenly. Sprinkle with more seeds as needed.

Step 7

In a medium frying pan over medium-high heat, warm the oil until just smoking.

Step 8

Frying two portions at a time, arrange the tuna steaks in the pan (do not overcrowd) and cook until the sesame seeds start to turn golden underneath, about 1 minute.

Step 9

Turn the tuna over and cook for 1 minute.

Step 10

Sear the edges of the tuna for 15 seconds on each edge.

Step 11

Transfer the tuna to a plate with a paper towel, gently patting to soak up any excess oil. Repeat with remaining tuna portions.

Step 12

Transfer tuna to a cutting board and cut ¼-inch thick slices.

Step 13

Arrange tuna on individual serving plates or bowls. Serve with pickled cucumbers and soy ginger lime sauce.