In a large saute pan, brown tofu on both sides in sesame oil, about 3-4 minutes. Set aside.
In the same pan, stir fry garlic, bean sprouts, and onions over medium-high heat so they brown, for 2-3 minutes. Add oil to pan, if needed.
Add reserved tofu, spinach, and soy sauce to pan and cook until greens are wilted, about 2 minutes. Toss all ingredients together while cooking to combine. Serve with rice.
