In a small bowl, whisk together the smoked paprika, garlic powder, onion powder, dried oregano, dried thyme, cayenne pepper, sea salt, and black pepper to create the Cajun seasoning.
Pat the shrimp completely dry with a paper towel and place them in a medium bowl, tossing thoroughly with the spice mixture until every shrimp is evenly coated.
Heat the extra virgin olive oil in a large cast-iron or stainless steel skillet over medium-high heat until shimmering.
Add the sliced bell peppers and diced red onion to the skillet, sautéing for 3-5 minutes until they are tender-crisp and show slight charred edges.
Push the vegetables to the outer edges of the pan and add the seasoned shrimp to the center in a single layer.
Sear the shrimp for approximately 2 minutes per side without moving them, until they turn pink and opaque with a golden crust.
Remove the skillet from the heat and drizzle the fresh lemon juice over the shrimp and vegetables, tossing everything together to deglaze the pan.
Spoon the warm cooked quinoa into a bowl and top with the smoky shrimp and vegetable mixture.