Drain the extra firm tofu and pat it dry. Break it into chunks and place in a blender. Add the plant-based milk, oil, white rice flour, potato starch, turmeric, garlic powder, Dijon mustard, black salt, and miso.

Blend on high speed until smooth and uniform, scraping down the sides as needed. The mixture should be thick but pourable. Let the omelette batter rest for 10–15 minutes at room temperature while preparing the fillings.

If using fillings that require cooking—such as potatoes, vegan bacon, or spinach—prepare them in advance and keep warm. Fried potatoes should be fully cooked and lightly crisped; vegan bacon should be browned and chopped; spinach should be wilted and any excess moisture removed.

Warm a nonstick or well-seasoned skillet over medium heat. Add 1 tablespoon of vegan butter. After 90 seconds when the butter is hot, pour in about ⅔ cup of the batter. Use the back of a spoon or spatula to spread the mixture evenly into a round, 6–8 inches (15–20 cm) wide.

Cook over medium heat for 4–5 minutes, or until the surface appears set and the underside is golden. Add the fillings to one side of the omelette.

Use a thin metal spatula to carefully fold the other side over the fillings. Cover the pan and continue cooking for 2–3 minutes, until the omelette is firm and lightly browned on both sides.

Transfer to a plate and repeat with the remaining batter, adding more vegan butter to the skillet as needed. Serve hot, optionally garnished with coarse ground black pepper, chives, or parsley.