In a large (10-inch) skillet, heat the oil over medium. Add the garlic and stir for a minute, then add the beans. Use an old-fashioned potato masher or back of a large spoon to mash the beans into a coarse puree. Remove from the heat and stir in enough water to give the beans an easily spreadable consistency, usually about 2 tablespoons. Taste and season with salt, usually about 1/2 teaspoon.