In a skillet, melt 1 tablespoon of butter over medium heat. Once bubbly, add panko and stir for about 5 minutes until golden brown. Remove from heat and cool on a plate.

In a mixing bowl, combine ½ cup mayonnaise, 2 tablespoons Sriracha, 1 tablespoon mirin, and 1 tablespoon lemon juice. Whisk until fully incorporated and chill.

Slice 1 cucumber into matchstick pieces and shred the crab meat. In a medium bowl, combine cucumber and crab, stirring gently.

Pour the creamy dressing over the crab-cucumber mix and toss gently until well-coated.

Arrange shredded lettuce on a serving platter, spoon the salad on top, and sprinkle cooled panko and sesame seeds before serving.