Thinly slice the leeks and garlic.
Heat the oil in a pan and gently sauté the leek gently until it's tender. Add the garlic and the wine. Let it sizzle and reduce it by half. Add the peas, bean, mint and the stock.
Bring to the boil and put the fish on top of the vegetables. Season to taste and sprinkle with the lemon zest. Add half of the lemon juice.
Put a lid on and simmer for about 10 minutes or until the fish is cooked through.
Drizzle the remaining lemon juice over it. Garnish with mint leaves and serve.