Heat the wet ingredients to dissolve. Stir together. This is your sauce.
Heat oil in a large pan until very hot (almost smoking). Add brussels sprouts, cut side down. Let them cook, undisturbed, until it smells a bit like popcorn (that’s them charring). Once they’ve charred a bit, start moving them around with a wooden spoon. Add a small pinch of salt to soften them. Cook to al dente. Reduce to medium heat. If rice cakes are fresh, add to brussels sprouts right away. If hard, microwave for 30 seconds on high, or blanch in boiling water for 30-40 seconds. Add rice cakes and sauce to brussels sprouts. Stir constantly until everything is glazed.