Ingredients
½ tuna steak
salt
freshly ground black pepper
2 tbsp olive oil
For the potatoes
½ potato, diced
1 lemon, juice only
2 tbsp olive oil
1 tbsp chopped chives and parsley
For the viniagrette
1 tomato, finely diced
½ lemon, juice only
¼ leek, finely chopped
¼ pack mushrooms, finely sliced
4 tbsp olive oil
1 tsp dijon mustard
salt
freshly ground black pepper

Method
1. Boil the potato in plenty of boiling, salted water. Drain well and return to the pan.
2. Stir in the other potato ingredients, slightly breaking up the potato dice but not mashing them.
3. Gently soften the chopped leeks in one tablespoon of olive oil.
4. Add them to a bowl along with all the other vinaigrette ingredients.
5. Stir through to mix and coat all the ingredients.
6. Season the tuna with plenty of salt and black pepper.
7. Sear in a hot pan for 1-2 minutes on each side so that it is still slightly pink in the middle.
8. Put the potato in a chef's ring to give it some shape and remove.
9. Serve the tuna on top and pour over the vinaigrette.