Cabbage & Carrots: Quarter the cabbage then dice to about 2-inch sections. Julienne carrots to matchstick thin. Rinse well and set aside to drain.
Salt: In a large mixing bowl, sprinkle 3 tbsp salt over cabbage and carrots and gently use your hands to rub the salt-in. Let them sit for 3 to 4 hours in a shady and cool area until the leaves are wilted. Rinse under cold water. Use your hands to gently squeeze out the liquid. Set them aside in an extra large bowl.
Kimchi marinade: Blend items under “kimchi sauce” from onion to pepper powder in a food processor until smooth. Combine cabbage, carrots, and scallions with the marinade. Mix and coat well (you can either use your hands with a glove or two wooden spoons to toss).
Pack: Place kimchi in glass jars with lid. Try to pack them down to close air pockets. Leave 1 inch at the top for air and gases. This will prevent it from spilling during fermentation process. Make sure the vegetables are covered with marinade on top. You can also place a large tray underneath to hold the jars and to prevent it from spilling.
Ferment: Seal the containers and store in a nice, shady, and cool area at room temperature for 2 to 3 days. After 24 hours, open the jar and pack it down with a clean spoon. Do this once per day until you are happy with the taste. You may notice some bubbling and this is perfectly normal. The longer you ferment, the stronger the flavor will develop. Once you move them to the fridge it will slow down the fermentation process. Best finish in 1 month.