Heat 1 tbsp of olive oil in a 20cm (8in) nonstick frying pan and gently fry 1 thinly sliced large onion for 4-5 minutes, until softened. Add 500g (14 1/2oz) peeled and thickly sliced potatoes and stir to coat in the onion mixture. Cover with a lid or foil and cook over a low heat for 20 minutes, shaking the pan from time to time, and turning them once, until the potatoes are tender. In a large bowl, beat 6 eggs together and season. Transfer the onion and potatoes to the egg mixture and mix thoroughly. Heat 1 tbsp olive oil in the frying pan and add the egg and potato mixture. Cook over a low heat for 8-10 minutes, without stirring, until set. Place under a preheated hot grill and cook for 2-3 minutes until the top is golden brown, or invert onto a plate and carefully slide back into the pan on the hob for a few minutes, to get both sides nicely golden-brown. Transfer to a board, sprinkle with a little smoked paprika and serve cut into wedges.