Pick most of the basil leaves into a pestle and mortar and bash to a paste with a pinch of sea salt. Peel and bash in the garlic, then pound in the almonds until fine. Muddle in 4 tablespoons of oil, finely grate in the Parmesan, then squeeze in the lemon juice. Season to perfection, and tweak to your liking.
Scrub and finely slice the potato, trim just the stalks off the beans, then place both in a pan of boiling salted water with the tagliatelle and cook according to the pasta packet instructions. Prep the delicate summer veg as necessary, adding them to the pan for the last 3 minutes. Drain, reserving a mugful of starchy cooking water, then toss with the pesto, loosening with a splash of reserved cooking water, if needed. Drizzle with 1 tablespoon of oil, and finish with the remaining basil and a fine grating of Parmesan. Nice served with a crunchy seasonal salad.