Cook the rice: Place the rice in a fine-mesh sieve and run under cold water for about 30 seconds. Let the water drain thoroughly and gently shake the sieve to remove any dripping water.

Bring 2 cups water to a boil in a 1½-quart pot. Add the rice, cover, reduce the heat to low, and cook until the rice is fluffy, 15 to 18 minutes. Season to taste with salt.

Make the sun butter sauce: In a small bowl, whisk the sunflower butter, coconut aminos, sriracha, garlic powder, ginger, salt, red pepper flakes, and ¼ cup warm water until you reach a pourable consistency. If the sauce is still too thick to easily pour, add up to 3 tablespoons more water. Set aside.

Prepare the cornflake-crusted tofu: Preheat the oven to 375°F. Line a large sheet pan with parchment paper and set aside.

Press the tofu block with a tofu press or wrap it in a clean kitchen towel or paper towels. Place the block on a plate and top with a heavy object, like a cast-iron pan or large can of tomatoes. Let sit until the excess liquid has drained, 15 to 20 minutes.

Meanwhile, in a food processor or blender, combine the cornflakes, garlic powder, salt, and black pepper and pulse until an even, sand-like texture is formed, about 30 seconds. (Alternatively, combine the ingredients in a large sealable plastic bag and crush using a meat mallet or rolling pin.)

Set up a dredging station with three medium shallow bowls. Add the tapioca flour to one bowl. Add the milk to the second bowl. Transfer the cornflake crumbs to the third bowl.

Slice the pressed tofu block horizontally in half. Cut each half in a 4 x 4-inch grid into 16 cubes (32 cubes total). Coat each cube in the tapioca flour, then the milk, and finally in the cornflake mixture. Evenly space the coated cubes on the prepared sheet pan to prevent steaming in the oven. Bake until the outsides are golden brown and crispy, 15 to 20 minutes.

Assemble the bowls: Spoon the cooked rice into four bowls. Top with the carrots, bell peppers, and cucumber. Set 8 pieces of tofu on top of the vegetables in each bowl. Drizzle with the spicy sun butter sauce and garnish with cilantro and green onions.