Preheat the oven to 375°F.
Place two paper towels on a cutting board and set the tofu on top. Put two more paper towels over the tofu, then place something heavy on the stack. Allow the tofu to sit for about 5 minutes.
Discard the paper towels and slice the tofu lengthwise into 4 slabs.
Pour the ponzu into an 11- x 7-inch baking dish, then place the tofu slabs in a single layer, turning to coat all sides.
Place in the oven and bake for 10 minutes. Remove, flip the tofu over, then bake for another 10 minutes.
Allow the tofu to cool in the pan, then cut each slab lengthwise into 3 strips and then into cubes.
Separate the chard stems from the leaves. Cut each stem lengthwise into thin strips, then dice.
Stack the chard leaves, then roll them up and slice into ribbons. Cut the ribbons in half crosswise.
Melt the coconut oil in a large skillet over medium heat. Once hot, add the onion, garlic, and chard stems, then sauté for about 5 minutes until the onion is translucent.
Add the crushed red pepper to the skillet and cook, stirring, for about 1 minute.
Add the chard leaves and water, then sprinkle with salt and pepper. Cook, stirring occasionally, until the chard is wilted and the pan is mostly dry, about 7 minutes.
Add the tofu to the skillet and stir to combine with the vegetables. Reduce heat to low and cook, stirring, for about 2 minutes until the tofu is warmed through.