Wo kann man Maissalat kaufen?

Is this babyleaf? If so, yes.

That’s called feltsalat(sometimes vårsalat) in norwegain. You get it in some bags of premixed salad that you get in most stores, especially bama mixes.

I have, however, never seen it sold on its own.

It does grow in the wild in norway from oslofjorden to the southern vestland, so foraging could be an option come spring.