Step 1

Heat oil in large saucepan over medium-high heat until shimmering. Add onions, celery, and green peppers and cook, stirring occasionally, until vegetables start to soften, 3 to 5 minutes. Stir in garlic and cook until fragrant, about 30 seconds.

Step 2

Stir in tomatoes, stock, hot sauce, Worcestershire sauce, bay leaves, white pepper, cayenne pepper, and thyme. Bring to a boil, then reduce heat to low. Simmer until sauce slightly thickens, about 20 minutes.

Step 3

Remove and discard bay leaves. Add butter and stir until completely melted. Remove from heat and stir in parsley and green onions. Season with salt, pepper, and additional hot sauce to taste. Sauce will keep in a sealed container in the refrigerator for up to 1 week.