• Season tuna steak evenly on all sides with salt and pepper. Combine black and white sesame seeds in a shallow bowl or on a plate. Press each side of tuna steak into sesame seed mixture, making sure the steaks are well-coated. Press gently to adhere the seeds to the tuna.
• Heat oil in a skillet over high heat until very hot. Sear tuna for about 1 minute on each side for medium-rare, depending on tuna's thickness.
• Remove from heat, let tuna rest for a few minutes, then dice (you can also serve tuna sliced thinly on nachos, if you prefer).
• Spread wonton chips, slightly overlapping, on a large serving platter.
• Top wonton chips with seared tuna, diced avocado, diced cucumber, diced mango, and chopped scallions. Add dollops of wasabi cream and drizzle on srircha and soy sauce, if desired. Place pickled ginger around.

Wonton Chips

• Add about 2 inches of oil (be sure to choose an oil with a high smoke point) into a large skillet or a pot. Use a thermometer to heat the oil to 350 degrees. (You'll also know oil is the right temperature by putting a piece of a wonton wrapper into the oil and having it immediately sizzle.)
• Add wonton triangles to the hot oil in batches, taking care not to overcrowd the pot to ensure they cook evenly.
• Fry wonton wrappers for about 30 seconds-1 minute per side or until they turn golden brown and crispy. Use tongs to flip. Use a slotted spoon to remove wonton chips from oil and place on a paper towel-lined baking sheet.
• Sprinkle salt over chips while they're still hot.
• If making ahead of time or if you have leftovers, store cooled wonton chips in an airtight container at room temperature.

Wasabi Cream

• In a small bowl mix together wasabi paste, sour cream, lime juice, and salt until well combined.
• Keep wasabi cream in fridge until ready to use.