This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well. The 布 part gets changed to ぶ, probably because if a food doesn't have konbu you say boo (ぶ).
I made broth with kombu.
Please tell me the difference between wakame seaweed and konbu seaweed.
"How dare you throw konbu seaweed at me!" "I’m sorry. I didn’t think it would be that big of a deal."