Why is 'selai' = 'jam' used here rather than 'mentega' = 'butter'. Jam is a fruit preserve, so what is peanut jam?
"Selai kacang" and "mentega kacang" are both acceptable terms for peanut butter. As for why "peanut jam" is an acceptable term, I guess Indonesians have a fairly expansive definition of "jam"!
Peanut butter aint butter either
English = Peanut butter
Dutch = Peanut cheese
Indonesian = Peanut jam/peanut butter