Method

1. Swordfish is a great alternative to tuna. It's just as melting and soft and it's a great fish to serve raw, which is the way you are going to put it on this tart.
2. It's going to go between the pastry base and a layer of tapenade, which is black olive and anchovy paste, with the Sauce Vierge on top.
3. Cut four rectangles from a roll of bought puff pastry.
4. Before baking it, cut around and make an indentation just inside the edges to make a frame for the dish.
5. Bake the pastry and put it aside to chill. Cut the fish into four generous chunks and sprinkle it with lemon juice.
6. Don't leave it in the juice too long or the juice will colour the fish - you just want to give it a tangy flavour.
7. Now you are going to make the Sauce Vierge.
8. Basically you just mix the ingredients and leave them to sit for a while.
9. Small fresh beans should be parboiled and put in a bowl.
10. The tomato should be peeled, de-seeded and finely chopped with the shallot.
11. Add the two, along with the tarragon and capers.
12. Finally add a good squeeze of lemon and leave it to sit and cool in the fridge.
13. To serve spread the tapenade on the pastry, place the fish on top and spoon over the Sauce Vierge.