Put the strawberries, vinegar, 1 tablespoon lemon juice and oil in a food processor or blender and process until smooth. Pass through a fine sieve or muslin cloth to remove the pips and set aside.
Season the scallops with salt and pepper and the remaining lemon juice.
Prepare the garnish. Heat the oil in a nonstick frying pan, add the leeks and cook over a high heat, stirring, for 1 minute, or until golden brown. Remove and set aside.
Add the scallop slices to the pan and cook for 20–30 seconds on each side. Divide the salad leaves into quarters and pile in the centre of individual serving plates. Arrange the scallop slices over the salad.
Heat the strawberry mixture gently in a small saucepan for 20–30 seconds, then pour over the scallops and salad leaves. Scatter over the leeks and garnish with the strawberries. Sprinkle with a little pepper and serve.