I was recently helping with some recipes and was instructed to use water for "sauteeing" onions, celery, garlic, etc in place of oil (scare quotes on "saute" since it involves frying in oil or other fat by definition).
The technique is meant to parallel sauteing in oil, water is measured by the tablespoon in a large pan, and although you replace waster as it evaporates the vegetables are never submerged in water. Only enough water is ever used to inhibit sticking of the vegetables to the own.
The results were good and light but I haven't had much of a chance to push it further and experiment with the upsides and downsides (the three dishes meant to just soften the onions, garlic, celery and I had to follow the directions). Obviously, using oils imparts that flavors that you otherwise won't have present if using water. More importantly though, I would like to know which reactions would be inhibited in some way; for instance, would browning and carmelizing happen at a different rate, or at all? Are there any other preparations that would be impossible without a fat to saute in? What are the limitations when using water to saute?