Heat a griddle pan until it gets really hot then put your asparagus on it. Put a heavy saucepan on top so it presses the spears right down onto the bars and makes lovely brown charred marks. Cook them for 2 minutes, turning halfway through. Pop the asparagus on a board and chop them in half on the diagonal.
Put the asparagus in a bowl with your tomatoes, half the larger basil leaves, olives, a splash of extra virgin olive oil and most of your lemon juice. Season with salt and pepper, then toss it all together and put to one side while you get the fish ready.
Rub your tuna with a little bit of oil and season. Sear for about a minute on each side. This will cook it rare – do it for 2 minutes on each side if you prefer it medium or 3 to 4 minutes each side if you like it well done.
Pound the remaining basil in a pestle and mortar then mix in the crème fraîche. Season and add some more lemon juice to taste.
Put the salad on a plate then break up the tuna and pop it on top. Spoon over some of the crème fraîche sauce and scatter over the baby basil leaves.
Nutritional information includes 1/8 teaspoon of added salt per serving, 1/4 cup of olives, and 1 tablespoon of olive oil. A handful is equivalent to Â¼ cup. A large handful is equivalent to 1/3 cup.