Bring a pan of salted water to the boil and boil the eggs for 9 mins, then drain, cool, peel and halve. Whizz the watercress and oil together with a pinch of salt and set aside. Mix the chilli flakes with some flaky salt and set aside. Everything can be prepared the day before and chilled, though there’s no need to chill the salt.

Take everything to the picnic in separate containers, then when you get there, scatter the eggs with the parsley and shallots, drizzle everything with the watercress oil and season with the chilli salt.