Thinly slice the large tomatoes and place in a wide shallow bowl.
Slice the cherry tomatoes in halves or quarters, and add them to the bowl. Drizzle with olive oil and vinegar. Sprinkle on a little salt and pepper and very gently toss to coat all sides of the tomatoes with the marinade. Let sit on the counter for 15 minutes while you organize the rest of the salad.
Arrange your greens around the perimeter of a large platter. Place the tomatoes in the center. Spoon on the marinade and any accumulated juices.
Top the salad with the crumbled feta cheese and pistachios. Add fresh cracked pepper to taste and enjoy.
Do not refrigerate the tomatoes at any time, either before, during, or after marinating. This salad is meant to be enjoyed asap. To make this tomato salad a meal, top with grilled shrimp.