Cook your rice according to package instructions. In a small pot, warm your rice vinegar, sugar, and salt until just about to boil, then remove from heat. Transfer the cooked rice to a platter, evenly pour the vinegar mixture on top, and fluff with a fork.

Remove the skin from the salmon. Pat the fish dry with a paper towel. Cube the salmon into 1.5-inch chunks. Season the pieces generously with salt, garlic powder, onion powder, chili powder, paprika, and dried oregano. Toss to spread the seasonings evenly.

In a large skillet, heat 2 tablespoons of sesame oil over medium-high heat. Working in two batches, add half of the salmon and cook for 3-4 minutes per side, turning gently. The internal temperature of the salmon should be no less than 145°F. Transfer the cooked salmon to a paper towel-lined platter. Wipe the pan clean and repeat with the remaining oil and salmon.

Whisk together the kewpie mayo, Sriracha sauce, and honey until smooth.

Divide the prepared rice among four bowls. Top each bowl with the cooked salmon, sliced avocado, julienned carrots, sliced cucumbers, diced scallions, and salmon caviar. Drizzle generously with the spicy mayo. Garnish with sliced nori strips and black sesame seeds.