Peel the cucumber, cut in half lengthways and slice.
Wash the peppers, halve, deseed and cut into thin strips.
Peel the onion and cut into thin rings.
Cut the feta into cubes.
Mix the vinegar, lemon juice, mustard, honey, salt and pepper and stir in the oil.
Place all the prepared salad ingredients in a bowl and pour over the dressing.
Tear the lettuce, add to the salad and serve.