1. Peel and finely chop the onion. Heat 2 tablespoons of oil in a frying pan and gently sweat the onion over a low heat until translucent.
2. Briefly raise the heat, add the sugar and leave to caramelise. Take the pan off the heat and set aside.
3. Pre-heat the oven in convection mode to 220°C/425°F/gas 7.
4. Peel, wash and thinly slice the potatoes. They do not need to be uniform, but should be about as thin as a crisp.
5. Lay the slices on a baking tray lined with baking parchment and brush with oil.
6. Roast in the oven for about 25 minutes, until the edges of the slices turn slightly dark and crispy.
7. Put the peas into a pan of boiling water and simmer for about 5 minutes. Drain and set aside.
8. Put the frozen spinach into a pan on a low heat and defrost. Drain and set aside.
9. Whisk the chickpea flour with the water in a bowl. Add the potatoes, onions, spinach, peas and parsley. Mix thoroughly and season well with salt.
10. Heat 1 tablespoon of oil in a non-stick frying pan.
11. Pour the potato mixture into the pan and spread out evenly. Cook over a low heat for about 10 minutes.
12. Use a turner to lift up the potato mixture from time to time to check. The underside should turn light golden and form a thin crust.
13. Then it is time to flip the omelette over. To do this, set a large, flat plate (with a diameter larger than that of the pan) over the pan and lay one hand on the plate. Use your other hand to hold the pan firmly. Then quickly, but without rushing, turn the whole thing over. The omelette will now lie on the plate. Return the pan to the heat, and use the turner to slide the omelette back into the pan without losing its shape.
14. Cook over a low heat for 10 more minutes, flipping the omelette several times so that it becomes evenly round. The surface should be a pretty golden colour. You can use a knife to check whether the inside is cooked. I recommend leaving the inside a little moist so that the omelette does not become too dry.
15. Rest the cooked omelette and allow to cool a little. Serve at room temperature.
Serve the omelette accompanied by a crisp salad.
Vegan Recipes from Spain by Gonzalo Baró, published by Grub Street Publishing, £18.99
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