sauteed garlic, onions and parsley
In Italian cookbooks, soffritto is generally understood as a mix of finely chopped garlic, onions and parsley sauteed in olive oil (in the south); in northern Italy, it's generally made with onion, carrot and celery. Meats, peperonicini, wine, giblets, or other ingredients may be added. It's the beginning of stews, soups and many other dishes.
Be careful though! In Campania, Calabria and the Basilicata, soffritto (or u suffrittu) can mean a stew of organs with tomatoes and peppers.