Salt the Cabbage
Cut 1 head napa cabbage into quarters lengthwise, then into 2 cm pieces. Add to a large bowl with 1 1/2 Tbsp coarse sea salt (iodine-free). Gently massage for 2-3 minutes until it starts to soften. Let rest for 2 hours, stirring occasionally, until the cabbage is wilted and sitting in a briny liquid.
Kimchi Paste
In a food processor, combine 1/2 small onion (chopped), 5 cloves garlic, 1/2 red apple (cored, chopped — use a sweet variety like fuji or honeycrisp), 1/2 Tbsp fresh ginger, 1/4 cup gochugaru, 1/2 cup vegetable broth, 2 Tbsp soy sauce, and 1 Tbsp white miso. Blend until smooth.
Transfer the paste to a large bowl along with 3 stalks green onions (cut into 5 cm pieces, sliced lengthwise) and 1 medium carrot (cut into matchsticks).
Combine
Rinse the salted cabbage under cold water to wash off the salt. Drain well, then give it a gentle squeeze with your hands to remove dripping water without wringing it completely dry.
Transfer the drained cabbage to the bowl with the paste and vegetables. Mix everything together with your hands to thoroughly coat every piece.
Ferment
Transfer to a mason jar and press down firmly with a spoon. Leave about 2 cm of breathing room at the top for gas produced during fermentation.
Close tightly with a lid. Leave on the counter overnight, away from direct sunlight or heat sources.
Open the lid the next day to release gas and taste for mild sourness. For a tangier taste, let it sit on the counter for 1-3 more days, burping twice a day.
The kimchi is ready to enjoy after 1-2 days. For more complex flavors, close the lid and refrigerate for 1-2 weeks to continue fermenting.
Fermentation is faster in warm weather (1 day) and slower in cold weather (2-4 days).
Store in the fridge for up to 3 months. Always use clean utensils when scooping from the jar.
Gochugaru (Korean red chili flakes) is the key ingredient — no good substitute. Find it at Asian supermarkets.
Use non-iodized salt for most reliable fermentation. If substituting red miso for white, use less as it's saltier and stronger.