Cook the lemon sole fillets according to the pack instructions.
Meanwhile, cook the green beans in a pan of boiling water for 2 minutes. Drain, and then put in a pan with the sliced shallots and 1 tablespoon of the oil.
Cook over a medium heat for a further 2 minutes until the beans are tender, then stir in the juice and grated zest of the lemon, another tablespoon of oil and the mustard.
Serve the fish with the cooked beans and shallots.