Mix the flour, water, and salt together and knead until combined. The mixture should be tacky but smooth. Rest for 15 minutes covered and then knead two more minutes until smooth. Cover with plastic wrap and allow to rest for half an hour in a warm place on the counter or in your oven under the proof setting.

Divide into two equal pieces. Roll into a 1/2-centimeter-thick sheet that is longer than it is wide. Coat the strip with oil, and place it on a parchment-lined tray covered with cling wrap and rest for an hour.

Prepare a pot of salted boiling water.

Cut into one- to three-centimeter pieces, about five to six per sheet. Pick up the ends of one of the pieces and pull gently. Jiggle a bit to encourage stretch without forcing too much to prevent breakage.

Slice through the center of the stretched noodle and open up the slit to form one long loop. Drop into boiling water for one to two minutes and drain.

Toss with sauce as detailed below.

Heat one teaspoon of oil in a frying pan. Add tomatoes, tomato paste, and oil to a frying pan until the mixture becomes thick.

Mix the tomatoes with the soy sauce, black vinegar, sugar, and sesame oil. Toss together with the noodles.

Add the white parts of the scallion, the garlic, gochugaru, Sichuan peppercorns, cumin, and sesame seeds to a heat-proof bowl.

Heat the oil until hot and fragrant. Pour over the scallion mixture. Quickly pour over the noodles and mix until coated.

Top with cilantro, green parts of the scallion, and slices of bok choy.