■ The basic idea: The hosts provide a side dish (almost always a salad), bread, and dessert (something simple; think fruit, cookies, pie, or brownies). Guests each bring a pot of soup along with empty containers with tight-fitting lids for the leftovers they will bring home after. You can coordinate the menu, but in our group we never talked about what we were making ahead of the party, and we never once had duplicate soups!
■ How many people? You can heat only four soups at a time (six to eight if you have an oversize stove top), so you don’t want to invite too many. Because we live in northern New England, we often use a woodstove — or even a fireplace — to reheat soup when we have an overabundance. You can also use a portable burner, slow cooker, or hot oven. If you want to have a big soup swap, think about heating half of the lighter soups first, swapping pots, and then reheating the remaining soups. Soup swaps can work with two people or 20; it’s just a matter of figuring out the logistics.
■ What should people bring? Ask everyone to bring a pot of soup, containers for leftovers, and a ladle to serve the soup. Most ladles look exactly alike, so it’s a good idea for guests to put colored string or tape with their names on the end. Generally the hosts provide spoons, bowls, napkins, forks, and plates if needed.
■ Portions: Be sure to pace yourself by sampling a little of each soup. You want to taste them all without getting too full. To that end, set out small bowls, mugs, or ½-cup ramekins rather than full-size bowls. The vessels don’t need to match; an eclectic collection looks great. Many of the cooks in my soup swap double the recipe they make, so there is one pot for eating at the party and one pot exclusively for leftovers. The take-home soup doesn’t need to be hot; it’s much easier to ladle at room temperature or chilled.
■ Drinks: Up to you. Many of us arrive with a bottle of wine or some beer. The host might provide soft drinks, coffee, and tea, and the guests can bring whatever else they would like.
■ Recipes: People always want the recipe if they particularly like a certain soup. So ask everyone to e-mail or print out his or her soup recipe to share with the group.
Themes: We never have themes, because we love the spontaneous way the meal comes together. I’ve spoken to others who divide up the soups — “You do an Asian-inspired soup, and I’ll do something Mediterranean” — or ask everyone to bring a childhood favorite.