We might more accurately say that Sauce Vierge is not so much in season as in fashion. It is one of the hippest sauces used by chefs in Ireland, many of whom have probably been turned on to the notion by the version in Gordon Ramsay's cookery book, Passion For Flavour.
Ramsay is an acolyte of Marco Pierre White, who includes a recipe for the sauce in one of his books, and White is an acolyte of the Roux brothers, who include the recipe in a number of their books. I have found it as far back as Michel Guerard's classic Cuisine Minceur, first published in 1976, but Escoffier and the Larousse Gastronomique don't mention anything like it. Simon Hopkinson, who includes a recipe for the sauce in his great book Roast Chicken And Other Stories, says: "To call it a sauce is a slight misnomer - it is more like a dressing." Whatever one calls it - and the name translates a something like "Virgin Sauce" though Guerard's translator calls it "Tomato Sauce" - it is a fresh and invigorating partner for some fresh white fish, simply grilled or roasted.
Here are two versions, chosen from among the changes chefs have rung with the idea. The Roux brothers simplified Guerard's version considerably, while Ramsay adds the modern elements such a shallot confit and balsamic vinegar. Both are superb.
Gordon Ramsey's Sauce Vierge Serves 6
6 basil leaves
6 large coriander leaves
6 coriander seeds
50 ml (2 fl oz, quarter cup) extra-virgin olive oil
2 tablespoons fresh lemon juice
1 heaped teaspoon Shallot Confit (see below)
half teaspoon balsamic vinegar
Sea salt and ground white pepper
Shred the basil and coriander leaves into fine, julienne strips, and crush the coriander seeds using a pestle and mortar.
Heat the oil and lemon juice very gently in a small saucepan then add the Shallot Confit, herbs, crushed berries, vinegar and seasoning.
Stir briefly, then remove from the heat and leave to infuse for at least five and up to 30 minutes. Serve the sauce warm, at room temperature or chilled.
Shallot Confit
8-10 large shallots, roots trimmed
150ml (quarter pint, quarter cup) extra-virgin olive oil
Rock salt
Sprig thyme
Bay leaf
Using a large, sharp cook's knife, chop the shallots into very fine dice.
Place in a heavy-based saucepan with the oil, a light sprinkling of salt, the thyme and bay leaf.
Set the pan over medium heat until the oil becomes hot, then adjust the heat to its lowest possible setting and continue to cook the shallots until they are meltingly tender - about two hours. Set aside to cool. Store in a screw-top jar in the refrigerator, where the confit will keep for up to one week, or, if covered with a layer of olive oil, for up to a month.
The Roux Brothers' Sauce Vierge au Basilic
200ml (8 fl oz) olive oil
2 medium tomatoes
1 garlic clove
8 tablespoons fresh basil
3 tablespoons snipped chervil
3 tablespoons snipped flat-leaf parsley
6 dried coriander seeds, crushed
Juice of 1 lemon
Fine salt, freshly ground white pepper
Plunge the tomatoes into a saucepan of boiling water for a few seconds; refresh in iced water, peel and deseed. Cut the flesh into very small lozenge shapes and place in a bowl.
Add the peeled, crushed garlic, the snipped basil, chervil and parsley and the finely crushed coriander seeds, the olive oil, lemon juice, salt and pepper.