2) Put the fish onto a baking tracy, rub with a little oil and some seasoning, top with most of the lemon zest. Roast for 8-10 mins until the fish flakes easily.
3) Meanwhile, cook the beans in a pan of boiling water for 3 mins until just tender. Drain, then tip into a food processor with the rest of the oil, garlic, basil stalks, lemon juice & stock, then pulse to a thick, slightly rough puree. Season to taste.
4) Divide the mash between two plates, top with the cod, then scatter with chopped basil leaves and the remaining lemon zest to serve.