In a mixing bowl, combine the chickpea flour, water, nutritional yeast, turmeric powder, mushroom seasoning, salt, and pepper. Whisk until smooth and well combined.
The batter should have a pancake batter-like consistency. If it's too thick, add a little more water; if it's too thin, add a little more chickpea flour.
Heat a non-stick skillet or frying pan over medium heat. You can lightly grease the pan with oil or cooking spray to prevent sticking.
Once the skillet is hot, pour a ladleful of the batter onto the center of the pan. Twirl the pan to ensure batter is spread into a thin, even layer.
Let the omelette cook for 2-3 minutes, or until the edges start to firm up and bubbles form on the surface.
Carefully flip the omelette using a spatula and cook for another 2-3 minutes on the other side, until golden brown and cooked through.
To a high speed blender, combine ingredients for the pea pesto and blend until smooth.
Stir fry veggies until they are cooked in olive oil and season them with salt and pepper.
Spread pea pesto on half the omelette. Fill in with vegetables and drizzle some more pea pesto on top.
Gently fold the other half of the omelette over the fillings to create a half-moon shape.
Serve!