We used tuna fillets (we like Ortiz), but any kind of oil-packed tuna will work. Keep the potato slices in a bowl of cold water to prevent discoloration, then pat them dry when you're ready to assemble the pie.
Preheat oven to 475 degrees. Form dough (as directed in Basic Pizza Dough recipe) in a 9-by-13-inch rimmed baking sheet. Arrange half of potato slices on top half of dough, the rest on bottom half, covering entirely; press into dough. Add olives, pressing into dough. Brush with oil and sprinkle with salt.
Bake until cooked through and crust is golden on edges and bottom, about 18 minutes.
Using a metal spatula, slide pie onto a cutting board. Artfully arrange tuna and remaining vegetables on top; sprinkle with vinegar and drizzle with more oil. (Alternatively, toss these ingredients together in a bowl, then top pie with salad.) Slice into 6 pieces and serve.