Gather a heavy-bottomed pot, a wooden spoon, and your chopped vegetables. Start by heating the vegetable oil over medium-low heat and gradually whisk in the flour. Stir continuously as the mixture darkens to a deep chocolate color, about 15 minutes, until it smells nutty and looks glossy.
Add the chopped onion, celery, and bell peppers to the roux. Sauté over medium heat, stirring frequently, until the vegetables are translucent and fragrant, about 8-10 minutes. You'll notice the vegetables soften and release their aroma, blending into the rich roux.
Gradually pour in the warmed stock while stirring vigorously to prevent lumps. Bring the mixture to a gentle simmer and cook for about 5 minutes until it begins to thicken and becomes glossy.
Stir in the smoked paprika, cayenne pepper, and Old Bay seasoning, mixing well. Let the sauce simmer gently for another 10 minutes, stirring occasionally, to deepen the flavor and develop a rich, thick consistency.
Gently fold in the raw shrimp, making sure they are submerged in the sauce. Cook for 3-4 minutes until the shrimp turn pink and opaque, being careful not to overcook them for tender bites.
Squeeze fresh lemon or lime juice over the shrimp and sauce. Stir well, allowing the citrus to brighten the flavors, and cook for another minute. Taste and adjust seasoning with salt as needed.
Remove from heat and let the étouffée rest for a couple of minutes. Serve hot over fluffy rice, garnished with chopped herbs if desired. The sauce should be thick, glossy, and bursting with smoky, spicy flavors, perfectly complementing the tender shrimp.
