Make the marinade by combining soy sauce, lemon juice, ginger, garlic, sugar, Sriracha, Worcestershire sauce, and ground pepper to taste. You can blend them as an option. Taste and adjust as needed.
Marinate for 1 to 8 hours in the fridge.
Combine tomatoes, mangoes, jalapeño, red onion, cilantro, lime juice, sugar, and extra-virgin olive oil in a bowl. Season with salt and pepper, then give it a taste. Refrigerate until ready to serve.
Preheat the oven to 450° F (230° C).
Arrange the tuna fillets evenly spaced on a baking sheet lined with aluminum foil (for easy cleanup). Drizzle with some oil.
Bake for 10 to 15 minutes, depending on the thickness.
Boil the leftover marinade in a saucepan until slightly thickened, then add butter. The sauce will be used for basting and serving.
Remove the tuna from the oven and baste it with the sauce. Broil on high for a few minutes until nicely charred.
Serve with the remaining sauce, some fried garlic, and tomato-mango salad.