In a large skillet, heat vegetable oil over medium heat.
Gradually whisk in the flour to create a roux. Stir constantly for about 15-20 minutes until the roux turns a light brown color, similar to peanut butter.
Once the roux is ready, add the chopped onion, bell pepper, and celery. Cook for about 5 minutes until the vegetables soften.
Stir in the minced garlic and cook for another minute until fragrant.
Add the chicken broth, tomato paste, cayenne pepper, paprika, thyme, bay leaf, salt, and pepper. Stir well to combine.
Bring the mixture to a simmer and cook for about 10 minutes, allowing the flavors to develop.
Add the shrimp and cook for an additional 5-7 minutes until the shrimp turn pink and are cooked through.
Remove the bay leaf and adjust the seasoning if necessary.
Serve the shrimp étouffée over a bed of cooked white rice.
Garnish with sliced green onions and chopped parsley as desired.