1. To prepare chicken, combine first 5 ingredients in a small bowl. Loosen skin from breast halves by inserting fingers, gently pushing between skin and meat. Rub the oregano mixture evenly under loosened skin of each breast half. Arrange chicken breasts in a shallow dish; cover and refrigerate at least 4 hours.
2. Preheat oven to 375°.
3. Heat oil in a large ovenproof skillet over medium-high heat. Sprinkle chicken with salt. Add chicken to pan, skin side down; cook 5 minutes or until browned. Turn chicken over, and transfer to oven. Bake at 375° for 25 minutes or until chicken is done. Remove chicken from pan, reserving 1 1/2 tablespoons drippings; set chicken aside, and keep warm.
4. To prepare sauce, heat reserved drippings in pan over medium-high heat. Add flour and 1/4 teaspoon cumin to pan, and cook for 30 seconds, stirring constantly with a whisk. Add chicken broth, 1 tablespoon tequila, and lime juice, scraping pan to loosen browned bits. Bring to a boil, and cook until reduced to about 2/3 cup (about 2 minutes), stirring occasionally. Serve with chicken.