burn (someone or something) to a crisp
1. To burn something, typically when cooking it, to the extent that it is completely charred and blackened. I forgot about the bread I'd put in the oven and burned it to a crisp.
2. To burn someone severely (typically referring to sunburn). Often used in passive constructions. If you lay on the beach all day without any sunscreen, you'll get burned to a crisp.
burn something to a crisp
to burn something totally or very badly. The cook burned the meat to a crisp.