Heat 1 tablespoon of the oil in a very large skillet over medium-high heat. Add half the shrimp, season with salt and pepper, and sear for 1 minute on each side, just so the shrimp start to turn a brighter pink on the outside. Remove with tongs to a plate. Repeat with another tablespoon of oil and the remaining shrimp, seasoning them as well, then add the second batch of seared shrimp to the plate.
Return the pan to medium heat. Add the remaining 2 tablespoons oil and when the oil is hot, add the onions and saute for about 5 minutes until they become tender. Add the garlic, oregano, and red pepper flakes, and sauté for one more minute until you can smell the garlic. Pour in the wine and cook until the wine has reduced by about half, about 3 minutes.
Stir in the tomatoes and bring to a simmer. Stir occasionally for 20 minutes, until the flavors meld and the sauce has thickened a bit.
While the sauce simmers, bring a large pot of salted water to a boil. Cook the pasta according to the package directions.
Just before the pasta is done, add the partially cooked shrimp and half of the basil to the tomato sauce and stir until the shrimp is hot and cooked through, about 2 minutes.
Drain the pasta, reserving ½ cup of the pasta cooking water, and return to the pot. Pour over the sauce with the shrimp, add the ½ cup pasta water, and toss to combine. Transfer to a shallow serving bowl, and top with the remaining basil. Sprinkle with some Parmesan or serve the shrimp dish with the Parmesan passed on the side for those who want it.
Notes
As with most shrimp dishes, the size of the shrimp is up to you. The larger the shrimp, the more expensive, but yes, the more dramatic the presentation. I stuck with extra-large here, which are usually labeled 21/25, as in 21 to 25 shrimp per pound. Please, go to jumbo if you like! If you are looking to wow a crowd, go to colossal, but remember to increase the final cooking time by a few minutes to make sure the shrimp are cooked through.