Preheat the oven to 375°F/190°C.
Cook the sushi rice according to the package instructions. Fold in rice vinegar, sugar, salt, and sesame seeds while warm. Set aside.
Season the salmon with salt and garlic powder. Drizzle with coconut aminos (if using) and chili crunch. Bake on a parchment-lined sheet pan for 10–12 minutes, until just cooked through, then flake with a fork.
Whisk together mayonnaise, sriracha, and sesame oil to make the spicy mayo. Adjust heat to taste.
Layer sushi rice in shallow bowls or on a platter. Top with flaked salmon, diced vegetables, avocado, and scallions. Drizzle with spicy mayo and eel or teriyaki sauce. Sprinkle with sesame seeds, nori/furikake, and crispy onions if desired.