Give tomato sauce a Greek twist by adding Kalamata olives, feta cheese, capers, and oregano.
Set a large pot of salted water to boil. In a medium saucepan, heat 2 tablespoons oil over medium-high. Add onion and garlic. Cook until soft, 5 minutes. Add tomato paste and oregano. Cook until fragrant, 30 seconds. Add tomatoes, tomato sauce, olives, and capers, if using. Cook, breaking up tomatoes with a spoon, until sauce thickens, 10 minutes. Season with salt and pepper. Reserve 2/3 cup tomato sauce for Baked Shrimp.
Meanwhile, cook pasta until al dente; drain. Add 2 tablespoons oil to pot and heat over medium-high. Add 3/4 pound shrimp and cook until opaque throughout, 1 to 2 minutes. Return pasta to pot and add tomato sauce; stir to combine. Serve pasta topped with 4 ounces crumbled feta.
Save the extra shrimp, feta, and tomato sauce to make Baked Shrimp with Tomato and Feta for tomorrow's lunch. Refrigerate reserved tomato sauce and remaining shrimp and feta separately in airtight containers.