Lay nori sheets on a dry, flat work surface. Lay spinach leaves in a single layer over the nori, leaving a ½-inch gap at the top of each sheet. Allow about a ½ inch or so of the leaves to hang over side edges for a decorative effect.

About 1 inch from the bottom of each sheet, lay salmon in a horizontal row on top of spinach. Spread cream cheese over salmon. Thinly slice avocado; just above salmon, arrange avocado in a horizontal row. Make a row of matchstick carrots and cucumber just above avocado.

Spread a thin layer of cream cheese across the top ½ inch of each nori sheet to help seal. Starting from the bottom, roll each sheet snugly to make a long, tight roll. Slice into 1-inch pieces with a sharp, serrated knife. Dip and eat.