Quarter cabbage lengthwise and chop each quarter into 3-inch pieces, discard root end. Add cabbage to a large bowl and rinse well with cold water. Drain out most of the water (it’s ok if you don’t get all of it out). Toss cabbage while sprinkling with kosher salt. Massage salt into leaves and let sit at room temperature at least 2 hours and up to 6 hours to allow liquid to release. Toss every 30 minutes or so. After cabbage is brined, rinse well in cold water several times until cabbage is no longer very salty. Drain excess water.

Set a small pot on the stove and add 1/2 cup water and 1 tablespoon glutinous rice flour. Bring to a boil and stir until a thick paste forms. Add sugar and stir until dissolved. Turn off heat and allow to cool completely. (If not using rice flour, just heat water and sugar until sugar dissolves and set aside to cool)

To the bowl of a food processor, add onion, garlic, ginger, fish sauce (or soy sauce), gochugaro, and cooled rice flour mixture (or sugar water) to bowl of food processor. Process until a coarse paste forms, scraping down the bowl, as necessary.

Add carrots, radish, pear (if using), scallions and chives (if using) to the bowl with the cabbage and toss together. Add spice paste and toss, with gloved hands, until vegetables are fully coated.

Divide kimchi and any liquid between jars, leaving 1" room at top of jar, packing it down as much as you can. Seal with a lid and let jars sit on countertop for 24 to 48 hours to allow fermentation to begin, then refrigerate. Flavors will deepen over time.

Do Ahead: Kimchi can be stored in the refrigerator for up to 2 months (or even longer). Open occasionally to release accumulated gas.