Anyone who is hungry heads to the dining tent, grabs a plastic plate from a mismatched pile and lines up under a sign that reads, “Lakota Rules: Women and children first.” All that is asked is that you take a minute to wash dishes, sort food or find some other way to pay for your meal with labor.

Ms. Buan, who owns the vegetarian restaurant Rosetta’s Kitchen in Asheville, was called upon during one trip to help figure out what to do with a donated buffalo that was hanging from the bucket of a bulldozer. On this visit, she is setting up a snug vegetarian kitchen that will feed about 30 of her family members and friends who plan to stay through the winter even if Energy Transfer Partners, the Dallas-based company building the pipeline, meets its goal and finishes the project by January.

Like almost every cook here, she will feed anyone who walks in.

The main kitchen is at the Oceti Sakowin camp, the biggest of four camps within a short hike of one another. Most of the meals are prepared in a military tent outfitted with a 12-burner propane stove and a few other large pieces of cooking equipment, including a black smoker just outside the door.

Members of the news media are warned that no images can be captured from within the main food tents, for fear that health inspectors might spot violations and use them as an excuse to shut down the camps.