Add oil to a skillet, when hot, add the onions, sauté until golden.
Add the harder vegetables such as carrots, peppers. When they are almost completely cooked add the broccoli and peas, stir for 1 minute.
Turn off the heat, and reserve the vegetables.
MAKE THE BATTER:
Preheat the oven to 180C (356F).
Add all the ingredients for the batter into the blender, except the baking powder. Blend well. You might need to add some water if your batter is too hard and difficult to blend.
Transfer the batter to a large bowl, add the baking powder and the sautéed vegetables, adjust the salt and pepper.
Grease a 7x7 inches baking tray, layer a parchment paper to it and grease it again.
Add the batter to the baking tray. Put it in the ovem for 40 minutes.
Remove from the oven and transfer it to a cooling rack.