This is what my mom made for us at the first sign of a cold, and as they say, Mom always knows best. Besides, this medicine is not at all hard to swallow.
Heat the olive oil in an uncovered large pot over low heat. Add the onions and parsley. Cover and cook over low heat, stirring frequently, for 30 minutes, until the onions are golden brown.
Add the water and raise the heat to medium. Cook covered, stirring frequently, for 30 minutes. Add the salt and pepper. Taste for seasoning.