for watercress salsa verde
Put the leaves and bread into the processor bowl with all the remaining salsa ingredients, except the oil. Whizz, gradually trickling in the oil to form a smooth sauce. Taste and adjust the seasonings. It should be slightly sharp but not too acidic. If necessary, add more oil or bread to dampen the sharpness. Pour into a bowl, cover and set aside.
Put the griddle pan over a high heat and leave to get outrageously hot. Brush the sirloin steaks with oil. Griddle for about 3-4 minutes on each side. Season. Let the steaks rest in a warm place for 3-4 minutes, and make a bed of watercress either on a serving plate or individual plates. Slice the steaks across the grain, and arrange on the watercress. Stir the salsa verde and then spoon a little artfully over the steaks, and serve the rest alongside.
Reproduced with kind permission of Sophie Grigson.