Braised lettuce and peas

1.Heat oil in a large deep-sided frying pan over medium-high heat, add onion and garlic, sauté until very tender (8-10 minutes). Add butter, cook until foaming, then add stock, lemon rind and mint, simmer until reduced by half (4-5 minutes). Add lettuce, turn occasionally until wilted (2-3 minutes), add peas and cook until just tender (4-5 minutes). Remove mint, season to taste, serve hot.