Why wouldn't you say "spicojn"?
Because "spicoj" is after the preposition "kun", which makes it drop the accusative
In German it would've become the dative case (prepositions and talking about dates)
how would you say " he mixes with spices"? is the accusative used on "spices"?
"Li miksas kun spicoj", so no, no accusative
In Esperanto, nearly after every preposition, no 'n' ending is needed. The exceptations are when the prepositional phrases indicate a direction (but never after ĝis, al, ktp.) : en la urbon (into the city) / en la urbo (in the city).
This one makes my mouth water each time.
I got this wrong by saying he mixed oil with spices. I guess "the oil" could indicate a specific oil rather than generic, but in everyday conversation i feel my translation is acceptable.
Mixed is past tense.
I got this sentence like 10 times now. I don't know why I keep getting it. :D