[@Remram]
That's really up to you, to be honest. Brom's your character and how he experimented, learned and gained the knowledge to cook and prepare food is your department. If he's eaten slime before? Then he already knows how. If he's never eaten a slime before? You'll just have to come up with some [b][i]totally (in)credible[/i][/b] reason for why he can figure out how to make it safe for ingestion.

Go wild! Go ham!
Mmm, haaaaaaam...