I am not sure what 上 means in this sentence. I know that 上 means above
or on
, but I think the meaning here is different because it does not mention anything above or on the sushi.
僕はいつもここでは握り寿司の上を頼むんだ。
Does it mean:
I always ask for the top hand-rolled sushi here.
i.e. best hand-rolled sushi?