Potlucks can be done in many different ways. There can be a theme, such as "dishes (or holiday food) from your heritage" ; salads; comfort food; soups, breads, and salads; team colors; produce from your garden/local; desserts only . . .
Break the ice, get to know each other, enjoy, socialize, raise awareness of diversity . . .
Each person brings food to share. Provide microwave, oven, refrigerator if necessary. Eating and serving utensilsand dishes. Arrange for places to eat. The organizers could provide a portion of the meal, such as beverages, desserts, and/or the main dish. Cards and markers for each person to indicate ingredients (these could be distributed ahead of time, so that people can bring them already filled out - they could be printed checklists or fill-in-the-blank for commonly allergens.
Because individuals may have food allergies and dietary restrictions, it is good to communicate about this ahead of time. Circulate a memo or post on a bulletin board: a list to be filled out by individuals, of foods and ingredients they cannot eat. It could be set up to maintain anonymity, if preferred. Ask everyone bringing in food to find alternatives to such ingredients if possible, and if not, to make sure they note the presence of the ingredients.
Schedule the event when everyone will attend and have adequate time for eating and socializing. Potlucks could be "put the food in the break room and everyone just come and get it when you can," but it is much more conducive to team building for all gather and eat together. Seating in small groups where everyone in the group can see and hear each other is more conducive to conversation than are long or very wide tables.
Set up food, serve, eat! If the group is large and/or not everyone knows each other, people can be encourage to sit with others they are not familiar with. The organizer could ask people to switch places periodically as a mixer, e.g., halfway through the mealtime, or before each course.
Discussions can include how to do a differently-themed or organized potluck the next time, such as: collaborate on making dishes together, invite other teams, sell each other the leftovers and donate the proceeds to charity . . .
A cooperatively themed dish, such as build-a-taco, -tortilla pie, or -salad, with everyone bringing any appropriate ingredients to add in. People could bring in the recipes for their dishes and archive a team cookbook collection. See also the Teampedia activity Stone Soup.