Cut very thin slices of pumpernickel bread, and spread them with an almost transparent layer of sweet butter. Arrange the bread around the bowl of vegetables. Serve thick chunks of garlic sausage, salami, or pepperoni; squares of feta cheese; and a bowl of plump black Greek olives along with the tartare of a perfect al fresco lunch beside the pool or at the beach. This vegetable mixture is much less rich than the original dish traditionally made with finely chopped or ground raw steak.
In a medium size bowl, toss together the zucchini, onion, tomato, bell pepper, and capers.
In a smaller bowl, beat together all the remaining ingredients, except the lettuce and chives, until thick and smooth. Stir this mixture into the vegetables.
Taste for seasoning and add salt and pepper if needed. Add the hot pepper sauce if using. Refrigerate 1 hour or more. To serve, mound the tartare on a bed of lettuce and garnish with the chives.