To avoid tearing, put the onions in icy cold water before peeling. Cut onion in half from the tip to the bulb end, and remove the outer skin. Place the onion half, cut side down, on a cutting board, and cut.
Whisk together the glutinous powder and 1/2 cup of water. Simmer over low heat, stirring occasionally, until it thickens to a thin paste. Mix all the seasoning ingredients in a large bowl.
Throw in the optional scallion and/or garlic chives. Store the kimchi in an airtight container. Onion kimchi can be eaten right away, but the flavor develops as it ferments over a week in the fridge.