1 tablespoon extra-virgin olive oil, divided, or to taste
Instructions
Preheat the oven to 400 degrees F (200 degrees C). Line a large baking sheet with parchment paper.
Cook the onions: Heat oil in a skillet over medium heat. Add onions; cook and stir until translucent, 6 to 8 minutes. Mix in chili powder, then stir in turmeric, coriander, cumin, and ginger until well combined. Remove from the heat.
Make the batter: Mix chickpea flour, cumin, coriander, and salt together in a bowl until well combined. Mix in onions and tomato purée, then add a little water until mixture is wet and easy to stir.
Drizzle 1 teaspoon olive oil onto the prepared baking sheet. Place 2 tablespoons onion mixture onto the baking sheet for each bhaji; flatten slightly with the back of a spoon.
Bake in the preheated oven for 20 to 25 minutes. Drizzle remaining oil over the bhajis and continue baking until golden brown, about 25 more minutes.