Combine all dry spices in a small bowl: salt, smoked paprika, oregano, garlic powder, onion powder, mustard powder, thyme, sugar, cayenne pepper, and black pepper. Stir well to ensure the spices are evenly distributed. I like to make this blend a few minutes before cooking so the flavors have a moment to meld together—it makes a noticeable difference in the final seasoning.

Place chicken breasts between two pieces of plastic wrap and pound to an even 1/2-inch thickness using a meat mallet. Pat the chicken dry with paper towels—this is crucial for getting a good sear. Lightly brush both sides of each chicken breast with grapeseed oil, then generously coat with the spice blend from Step 1, pressing gently so the spices adhere to the meat.

Heat your grill or cast-iron skillet to medium-high heat (around 400°F if using a grill; medium-high on the stovetop). Once hot, carefully place the seasoned chicken on the grill or pan. Cook for 2-3 minutes without moving it—resist the urge to flip or shift the chicken, as this prevents the spices from developing that signature dark, caramelized crust. Flip and cook the second side for another 2-3 minutes until the internal temperature reaches 165°F and the chicken is cooked through. I find that letting each side develop a proper char without constant movement is what separates good blackened chicken from great blackened chicken.

Remove the chicken from heat and let it rest for 5 minutes on a warm plate. This allows the juices to redistribute, keeping the meat tender and moist. Serve with fresh lemon wedges on the side for brightness that cuts through the rich, smoky spice crust.