Cut the tofu in half horizontally and lay between layers of paper towels. Place on a plate, top with another plate, and place a weight on top (a 14-ounce can of vegetables works well). Let stand 20 minutes. After 20 minutes, cut the tofu into 1/4-inch cubes and place in a large mixing bowl. Add the carrots, cabbage, red pepper, scallions, ginger, cilantro, soy sauce, hoisin, sesame oil, egg, salt, and pepper. Lightly stir to combine.
To form the dumplings, remove 1 wonton wrapper from the package, covering the others with a damp cloth. Brush the edges of the wrapper lightly with water. Place 1/2 rounded teaspoon of the tofu mixture in the center of the wrapper. Shape as desired. Set on a sheet pan and cover with a damp cloth. Repeat procedure until all of the filling is gone.
Using a steaming apparatus of your choice, bring 1/4 to 1/2-inch of water to a simmer over medium heat. Spray the steamer’s surface lightly with the non-stick vegetable spray to prevent sticking. Place as many dumplings as will fit into a steamer, without touching each other. Cover and steam for 10 to 12 minutes over medium heat. Remove the dumplings from the steamer to a heatproof platter and place in oven to keep warm. Repeat until all dumplings are cooked.
To make dipping sauce, whisk together ingredients in a small bowl.