Place the tortilla on a cutting board. (If it's not at room temperature, warm it for 5 seconds in the microwave so it's soft and easy to roll.)
Spread the nut or seed butter on, leaving about 1/4-1/2 inches around the edges.
Add the banana to one end. Fold the tortilla over the banana and tightly roll up.
Serve, cut in half, or slice into rounds with a serrated knife. Serve immediately.
Notes
This wrap is best served soon after making, though if you want to pack it in a kids lunch box, you can either leave the wrap uncut or stand the pieces up side-by-side right next to each other (so it will look like you just cut through the wrap) to limit the air that touches the sliced banana.
Use a fajita-size flour tortilla so this is easy to roll up and easy to bite through.
Use any nut or seed butter you prefer.
Try to roll the banana tightly in the tortilla.
A straighter banana makes this a little easier to roll.
Serve with milk, a smoothie, or another easy side your kids like.
Know that younger kids may pull each one of these slices apart and eat them that way!