Put all sauce ingredients in a microwave-safe container and heat on high for 90 seconds, just until it starts to boil. Let it rest for about five minutes.
Pour about one third of the sauce into a low, wide container, add tofu in a single layer, and cover with the rest of the sauce. Cover the container and refrigerate for at least a half hour and up to three days.
Grill marinated slabs of tofu for three or four minutes, until heated through and the grill marks look the way you want them to look. Or bake cubed tofu at 350 for 8 to 10 minutes, turning halfway through. Refrigerate any extra for up to five days.