Get something cooked like shrimp tempura or a veggie roll. Futomaki is a nice mix of some pickled veggies. They definitely have shrimp tempura roll. Yellowtail is a very mellow fish. The mahi-mahi was similar. I’d go with a lighter tasting fish before you go with one stronger in taste.

I would suggest a maki roll which is dried seaweed aka nori. Those have a multitude of fillings and will help ease your palate into eating raw fish. Then move to nigiri style which is a piece of fish on top of sushi rice. Sashimi is thinly sliced fish, no rice. I wouldn’t suggest that for a sushi newbie. Enjoy 😉

The green stuff is wasabi so use very little at first.