Tear the lettuce leaves into bite-size pieces and put them in a salad bowl. Cut the tomatoes into wedges or slices, then add them to the bowl.
Heat the oil in a small saucepan over low heat. Mince the garlic and add it to the pan. Cook 1 min, with stirring, then pour in the vinegar and mustard. Warm through and season to taste with salt and pepper.
Pour the dressing over the salad, then add the tuna, olives, and Feta cheese. Toss well and serve.
I made a couple of changes to the recipe. I used romaine lettuce and didn't dress the salad. Dear hubby is a fussy eater. He used ranch dressing and I used spicy Italian. DELICIOUS!