Begin by preparing your tofu. Drain any excess water and wrap in a kitchen towel to gently press out moisture. Slice it into 2 pieces lengthwise (so you end up with 2 "steaks") and then use a knife to score diagonal lines across the surface of each steak. Repeat, scoring perpendicular lines this time.
In a shallow dish or tupperware container, mix together the garlic, soy sauce, rice wine, coconut sugar and five spice. Add your tofu steaks and let marinate for about 15 minutes, then flip and let marinate again.
While the tofu is marinating, start your sauce. Add a touch of neutral oil to a pan and once hot, add dried shiitake mushrooms and shallots. Sauté for 2-3 minutes, then add garlic and sauté for another minute.
Add soy sauce, coconut sugar, rice wine, five spice and black pepper to the pan and use a spatula to ensure the coconut sugar is dissolved. Add water then bring the mixture to a boil and reduce the heat to a low simmer. Let simmer for about 30 minutes.
When ready to serve your steaks, dust with cornstarch or arrowroot powder and heat neutral oil in a pan (use enough to cover the surface of your pan). Once hot, place your steaks in the pan, score side down first and flip once golden brown. Once both sides are cooked, serve over rice and pour a ladle of sauce on top of the tofu steak.
Garnish with scallions and mustard greens.