Using “allium” as an adjective

Solution 1:

Alliaceous is used botanically for plants of the garlic/onion family; might it fit the bill? (It’s much more standard than allial, I think, going both by dictionaries and google.)

Now I want to go out and order something big and garlicky at a restaurant, just so I can smack my lips and say “Mmmmm! Alliaceo-licious!”. Or, not quite, because it would just confuse people. But I’m enjoying the idea…

Solution 2:

Allium is already used in English to mean "a bulbous plant of a genus that includes the onion and its relatives". You could use allium as modifier.

_{[Reference: the New Oxford American Dictionary.]}