Tuna and Egg Sandwich with Garlic Vinaigrette

INGREDIENTS
1/2 onion, thinly sliced
1/2 cup olives, pitted and chopped (optional)
2 hard-cooked eggs, peeled and sliced
8 slices country bread
1/2 recipe Martha's Favorite Vinaigrette
Romaine lettuce
2 6-ounce cans drained tuna

DIRECTIONS
1.Soak 1/2 onion, thinly sliced, in very cold water for 20 minutes. Drain on paper towels. Pit and chop 1/2 cup olives (optional). Peel and slice 2 hard-cooked eggs.
2.Brush 8 thick slices country bread on one side, using one half recipe of garlic vinaigrette. Make sandwiches, layering romaine lettuce, two 6-ounce cans drained tuna, olives, onion, and eggs.