Cut lettuce into leaves, rinse, pick and drain. Rinse tomatoes, remove stalks and cut into thin slices. Rinse cucumber, quarter lengthwise, then cut into larger cubes. Halve peppers, clean, rinse and cut into narrow strips. Remove skin from onions and cut into fine rings. Cut feta into bite-sized cubes.
For the marinade, stir vinegar with salt, pepper and Organo until the salt is dissolved. Now fold in the olive oil.
Mix all the salad ingredients (minus the cheese) in a baking bowl, add the marinade and mix well. Spread the feta cubes evenly on the lettuce.