Preheat the oven to 200°C

The batter

• Mix well the first 4 ingredients, add salt, pepper, (and curry if you want) and let it rest for at least 3 hours in the fridge (better to leave it overnight in the fridge).

The Fillings

• Cook the onion over low heat in a covered non-stick frying pan and stir occasionally until they are nicely golden brown (it will take +/- 10 mins)
• While waiting for the onion to be ready, heat the oil in the frying pan and put in the potatoes, cook them until they are all golden brown and soft. Lift them up and put them on a paper towel to get rid of the oil excess.

Baking time

• Spray or brush the rounded baking pan with oil to avoid the tortilla becomes sticky or you can also cover it with parchment paper.
• Put together the cooked onion and potatoes in the baking pan then stir in the batter, mix well (add salt and pepper if needed).
• Bake them at 200°C for 40 minutes, let them rest for 10 mins in the oven then serve them hot.