Here's a recipe for caramelizing onions in the microwave. It's a lot cleaner and easier than doing it on the stove. My Parsi friend keeps a supply on hand at all times - she adds a little butter or ghee to the oil, and just a pinch of cumin - to sprinkle on rice and plain boiled toor dal. This technique is from Moghul Microwave by Julie Sahni.

Heat the oil in an 8-inch microwave-safe skillet at 100 percent power in a 650-700 watt carousel oven for 2 minutes. Add onion slices and stir to coat them with oil. Cook at 100 percent power for 7 minutes (or until onions turn caramel brown), stirring twice. Watch carefully during the last 2 minutes of cooking as the onions, after losing their moisture, fry rapidly and can overbrown and burn. Remove from oven and drain on paper towels. Reserve the excess onion-flavoured oil for other uses. Can be stored in a closed container at room temperature for two days, or in the fridge for up to a week.