Using gloves, cut the chili in half. Remove the seeds and pith for less heat, or you can opt to keep the seeds and pith intact to increase the spiciness.
Place the cut chili into the balsamic vinegar and cover with cling film.
Refrigerate for 2 hours to allow the balsamic to become spicy.
Remove the vinegar from the fridge and remove the chili halves ensuring you remove any seeds which may have fallen out.
Heat a saucepan over high heat and add the balsamic and sugar.
Stir until the sugar is dissolved then reduce the heat to low.
Simmer until the mixture has reduced to around a quarter of the original volume (½ cup).
Serve with your favorite grilled meat or use as a marinade for chicken or pork.
Any chili pepper works in this recipe. But if possible, opt for a chili pepper that is less fragrant/sweet to keep the flavor balance just right. Fresh cayenne peppers work well here. For less heat, jalapeños are a good place to start.