Roughly chop first 6 ingredients. In food processor, pulse until finely chopped for sofrito. In ovenproof skillet, heat oil over high. Brown chicken, skin side down, 8 minutes; transfer to plate. In the same skillet, cook sofrito until fragrant, 2 minutes. Add stock and chicken, skin side up. In oven, roast at 400° until cooked through, about 20 minutes.