Every once in a while, I'll caramelize an onion or two and use it all week - they are perfect for paninis, salads, pizzas, etc. It doesn't take much just an hour on the stove in the afternoon.... Since I work Saturdays and have Mondays off, I usually make a mess in my kitchen Monday afternoons between dinner and a couple things for lunch during the week.
1-2 onions, peeled and chopped
drizzle olive oil
drizzle balsamic vinegar
salt and pepper to taste
sprinkle of sugarHeat olive oil in a shallow pan (with a lid) over low heat. Add onions and remaining ingredients, stirring to combine. Cover and cook for about an hour over low heat. Remove from heat and transfer onions to an airtight container and keep chilled.