Colorful Korean Dumplings (Mandu)

Fill a large pot with lightly salted water and bring to a rolling boil; stir in noodles and return to a boil. Cook noodles uncovered, stirring occasionally, until tender yet firm to the bite, 6 to 7 minutes. Drain and dice.

Place cabbage, onion, bell pepper, carrot, garlic, salt, and pepper in the bowl of a food processor; pulse until vegetables are diced.

Heat olive oil in a pan over medium-low heat. Saute the vegetable mixture in the hot oil, stirring frequently, until soft, about 6 minutes. Add tofu; saute for 5 minutes.

Place filling in a cheesecloth and squeeze as much water out as possible. Transfer the filling to a bowl and mix in the diced noodles, scallions, and sesame oil until well combined.

Mix flour, beet juice, egg, and salt for dough together in a bowl and knead until cohesive but not sticky.

Roll out dough with a thin rolling pin, or roll it through your pasta machine at the thickest setting. Progressively roll the dough thinner until it reaches the second-thinnest setting on your machine--or, thin enough that it's see-through, but not quite transparent. Cut circles for dumpling wrappers with a 3 1/2-inch biscuit cutter or cup. Roll excess dough back through the machine, or with a rolling pin, repeating the process and cutting out more wrappers until you have no more dough left.

Place about 2 teaspoons of filling in the center of each dumpling wrapper. Fold each wrapper in half and pinch all the way across until the dumpling is sealed firmly shut.

Place a steamer insert into a saucepan and fill with water to just below the bottom of the steamer. Bring water to a boil. Working in batches, add dumplings, cover, and steam until heated through, about 10 minutes.