Method-
Rinse and spin dry the lettuce and spinach leaves.
Tear into bite-sized pieces and place in a salad bowl.
Add the cubed tomatoes and cucumber to the leaves in the salad bowl.
Chill in the refrigerator.
Mix the oil, vinegar, salt and pepper in a small bowl and keep aside.
Pour dressing over the salad just before serving.
Add the chopped walnuts.
Toss the ingredients gently to mix them well.