My family was vegetarian from 1998 to 2004 while my cousin from India was living with us and attending college. Coincidentally, my mom was teaching a cooking class at the time she called “The Occasional Vegetarian.” I used to go with her every week to prep beforehand, chopping piles of garlic and onions, and pretending to do homework while she taught, but secretly listening in. I wasn't surprised (or upset) to find these in my lunch box the day after the rice ball class.
Heat sesame oil in a large skillet over medium heat, then sauté garlic for 2-3 minutes. Reduce heat to low, add spinach and sauté until just cooked through, another 2-3 minutes. Toss with sesame seeds and set aside to cool.
Line a small bowl or ramekin with plastic wrap and loosely press a 1-inch layer of rice into the bottom. Add 2 tablespoons of spinach to the center, then add another layer of rice on top to cover.
Fold the sides of the plastic wrap in, then twist to make a sealed package. Flatten the rice ball between your hands. Mold it into a triangular shape, apply firm pressure with both hands, then remove plastic wrap.
Lightly press a nori strip around the bottom of the rice ball, sprinkle with sesame seeds if desired, and serve.