This jam is a wonderful accompaniment to bread and sharp cheeses and can be made with almost any medium-hot chile. (Do not use habanero or Scotch bonnet chiles.) Green chiles are fine, but red chiles produce a spectacular color. Wear thin latex or rubber gloves when handling chiles to prevent any skin irritation, and remember to keep the gloves away from your face and eyes.
How to Make the Ultimate Umami-Bomb Vegetarian Demi-Glace
1 small onion, quartered and thinly sliced
1/2 cup sugar
1/3 cup minced seeded medium-hot chiles, such as jalapeños or serranos
1/4 cup minced red bell pepper
1/4 cup water
1/4 lemon, cut into 2 wedges and seeded
Large pinch of salt
Combine all of the ingredients in a medium saucepan and bring to a boil. Cook over moderate heat, stirring often, until the jam thickens and registers 210° on a jelly thermometer, about 12 minutes. Discard the lemon wedges. Pour the jam into a clean jar or container and refrigerate for up to 2 weeks. Warm the jam slightly in the jar set in a saucepan of gently simmering water before serving.