In a small bowl whisk together all ingredients for the Spanish seasoning mix. Divide in half and set aside. Cut the lemon in half, then thinly slice one half - for garnish - and reserve the other half for juicing later in the recipe.
Place chicken in a medium bowl. Drizzle with 2 tablespoons oil, then toss to coat well. Use half of the prepared seasoning mix to rub on both sides of each piece of chicken.
Drizzle a large skillet with remaining 1 tablespoon of oil and bring to medium heat. Cook chicken for 2-3 minutes on each side until browned. Transfer to a plate. (It won't be cooked through at this point)
Add rice, chicken broth, juice from 1/2 of the lemon, and remaining seasoning mix and stir to combine. Return chicken to the pan on top of the rice. Cover and cook for 20-25 minutes until liquid is absorbed, rice is tender, and chicken is cooked through.
Garnish with lemon slices and freshly chopped cilantro or parsley and serve immediately.
*Coriander is found in the spice section of any typical grocery store. In a pinch, cumin can be used as a substitute.