Literary and rare. In this reading 焯 means 'clear, bright, evident', surviving mostly in the bookish phrase 焯然 ('strikingly clear'). The everyday reading is chāo, the cooking verb 'to blanch'.
The fire radical on the left ties this character to heat and cooking — fitting for a verb about plunging food into boiling water. It groups 焯 with the large family of stove-and-flame characters.
Carries the sound. Standalone 卓 reads zhuó; here the reading has shifted to chāo for the cooking sense (and the rarer zhuō reading 'clear; evident' keeps closer to it).
