Heat the oven to 220C/200C fan/gas 7. For the dressing, put the tuna, anchovies, garlic, Dijon, egg yolks, some black pepper and a little salt in a food processor. Blitz while slowly adding the oil, a drop at a time, letting the mixture thicken between each addition. Add the vinegar, taste and add however much lemon you think it needs. Stir in the capers. The mixture shouldn’t be as thick as mayonnaise – you should be able to drizzle it. If it’s too thick, whisk in water 1 tsp at a time to loosen.

Put the beans onto one or two baking trays where they can lie in a single layer. Add the olive oil, toss with your hands and roast for 8 mins. Put some of the tonnato dressing on a platter, then spoon the beans on top. Drizzle with more of the dressing and scatter over the parsley. Offer the rest of the dressing on the side.