Cook the broad beans in a pan of boiling water for 3-5 minutes. Drain and refresh in cold water. When cool enough to handle, remove the skin from each bean, use your nail to slit the skin, then pop out the bright green bean. Whisk the olive oil, lemon juice, garlic and chilli flakes together in a bowl and season, to taste, with salt and freshly ground black pepper. Mix the cooked couscous, broad beans, avocado, apple, spring onions and radishes together in a bowl, add the dressing and toss gently. Add the cress, give the salad one further toss and serve with your favourite barbecued cuts of meat or chicken