Combine red pepper, serrano pepper, red onion, vinegar, olive oil, chili sauce and kosher salt to make the vinaigrette.
Mix well and set aside.
Season tuna with salt and pepper.
Sear tuna on a very hot skillet with olive oil.
Cook to desired doneness (rare if preferable).
Prepare the salsa while the fish is cooking.
Dice the avocado into 1 cubes.
Dice the tomatoes.
Mix the tomato and avocado together.
Place fish on serving dish.
Top with diced avocado and tomato.
Splash liberally with vinaigrette.
Garnish with cilantro.
Again, I like to add a little soy sauce to the vinaigrette to give the flavors a little more punch, I only use 2 tablespoons olive oil in the vinaigrette to make it more bulky, and I like to garnish the fish with chopped cilantro instead of sprigs.