Make the tuna salad: In a bowl, mix together the tuna, mayo, soy sauce, sweet chili sauce, sriracha, mustard, and cream cheese until smooth. Fold in the red onion, jalapeños, and fresh dill. Season with salt and black pepper to taste.
Build the sandwich: Start with a base of grilled or toasted focaccia. Add a generous layer of the spicy tuna salad. Top with slices of cheddar cheese. Add lettuce, tomato, and extra jalapeños if you’re brave. Close with the second piece of focaccia.
Optional: Grill or press the whole sandwich until the cheese melts and the focaccia is golden and crisp.