Place the veggie broth, chickpea flour, nutritional yeast, Vegg powder, salt and pepper into a blender and puree until completely smooth.
Warm the same large cast-iron pan over medium heat, and coat with a thin layer of oil.
Pour the omelette batter into the hot pan and cook for 3 minutes before filling half of the omelette with the sautéed veggie mix.
Cook for an additional 2-4 minutes, until the edges brown and lift slightly, making sure to pop any large bubbles.
Carefully separate the edge of the omelette from the pan and use a large spatula to flip the empty half on top of the veggies. Adjust heat to very low, just to keep warm while preparing the sauce.