Cut each head of napa cabbage in half lengthwise and trim the core. Rinse under cold water, then chop into 2-inch squares.

Place cabbage pieces in a large resealable bag. Sprinkle with kosher salt, massaging leaves to distribute evenly. Seal the bag and let it rest at room temperature for 6 hours, flipping halfway.

Rinse the cabbage thoroughly to remove excess salt. Drain in a colander for 15 minutes.

In a bowl, combine gochugaru, fish sauce, minced garlic, grated ginger, and sugar. Stir into a smooth paste.

Return drained cabbage to a clean bowl. Add the spice paste, sliced green onions, and carrots. Massage the paste into the cabbage until well coated.

Transfer the kimchi into a sanitized glass jar, pressing down to remove air pockets. Leave about 1 inch of headspace.

Seal the jar and let it ferment at room temperature for 1–2 days until bubbling appears. Then transfer to the fridge to ferment slowly for up to 2 weeks.

Serve your homemade kimchi as a tangy Korean side dish, add to stews, bibimbap, or rice bowls.