Heat 2 tablespoons olive oil in a large pan over medium-high heat. Add shrimp and sauté until shrimp just turn pink, 3 minutes. Remove shrimp from pan to a separate plate.
Add 1 finely chopped onion and sauté until translucent, about 7 minutes. Add 4-5 minced garlic cloves and continue cooking with onions until the garlic is fragrant, another 3 minutes. Sprinkle with 1 teaspoon dried oregano and 1-2 teaspoons crushed red pepper and sauté for 2 minutes to release the fragrance.
Add 1 28-ounce can of tomatoes that have been crushed by hand, 1-2 cups of chicken stock (depending on preferred consistency for sauce), and ¾ teaspoons sea salt. Turn up heat and bring to a gentle boil, then reduce heat and simmer sauce for 20 minutes.
Taste spicy tomato sauce and add more salt if needed. Stir in cooked shrimp and continue simmering until shrimp are completely cooked through, 3 minutes.
Transfer Shrimp in Spicy Tomato Sauce to serving dish. Garnish with chopped fresh parsley.