Toss shrimp in a bowl with 1 tsp. salt and 1 tsp. red pepper, and oregano.
Heat oil in skillet on medium high heat. Add shrimp, sauté 1-2 minutes. Transfer shrimp to large plate.
Add onion to same skillet, with 1-2 T. oil, sauté until translucent (about 5 minutes). Add tomato with their juices, wine, garlic, and oregano. Simmer until sauce thickens (about 10 minutes).
Return shrimp to skillet with accumulated juices, toss to coat and cook 2 minutes more. Stir in parsley, serve immediately.