Heat the vegetable oil in a large saucepan over medium heat. Get ready for the sizzle!
Add the chopped onion, green bell pepper, and celery. Cook until softened and fragrant, about 5–7 minutes.
Stir in the minced garlic and cook for another 30 seconds, just until it releases that irresistible aroma.
Add the diced tomatoes, tomato paste, and chicken broth. Stir everything together to make a saucy base.
Sprinkle in the paprika, cayenne pepper, thyme, oregano, salt, and pepper. Drop in the bay leaf if using. Give it all a good stir!
Bring the sauce to a gentle simmer. Let it bubble happily for 15 minutes, stirring occasionally to let the flavors meld.
Once the sauce has thickened slightly, remove from heat and stir in the lemon juice or vinegar for that bright finishing touch.
Taste and adjust seasoning if needed. If you like it spicier, go ahead and add a pinch more cayenne!
Garnish with fresh parsley if desired, and serve hot over your favorite dishes — seafood, chicken, rice, or veggies!