- Heat the oil in a large non-stick frying pan, about 28cm diameter. Saute the potato and onion, turning gently, for about 15 – 20 minutes or until almost cooked but not browned.
- Gently beat the eggs, salt, cheese and cayenne pepper together in a large bowl. Using a slotted spoon, gently transfer the potatoes and onion to the egg mixture leaving behind as much oil as possible. Gently toss to combine then pour back into the hot pan, evenly spreading out the mixture.
- Cook, covered for 5 – 7 minutes over low heat, gently shaking the pan. Gently slide a spatula around the edge of the pan and place a large flat plate or tray over the top. Quickly turn onto the plate then gently slide back into the pan. Cook for a further 3 – 5 minutes or until firm and cooked.
- Remove from the pan and leave to cool to room temperature before serving. To prepare the sage leaves, heat olive oil in a pan so it just covers the base. Place sage leaves in, a few at a time and turning once, until darkened in colour but still green. Remove and place on kitchen paper. Serve the tortilla cut into pieces about 2 – 3 cm square and top with relish and a crispy sage leaf.