Bottom four-dot fire (under-form of 火) - anchors 焦 in the cooking family alongside 热 (hot), 煮 (boil), 蒸 (steam), 然 (originally 'to burn'). The four dots picture flames licking up; here they char the bird above into the burnt-black state of 焦.
Top 隹 - pictograph of a short-tailed bird, same component in 集 (gather), 难 (difficult), 雀 (sparrow), 雄 (male). With 灬 underneath, the picture is a bird roasted over fire, charred - the original sense of 焦. Compound ideograph, no phonetic.
