Preparation Cook onion in butter in a 12-inch heavy skillet over medium heat, stirring occasionally, until softened, about 5 minutes. Add beets, water, and 1/2 teaspoon each of salt and pepper and simmer, covered, until beets are tender, about 20 minutes. Uncover and cook, stirring occasionally, until liquid has evaporated, 2 to 5 minutes. Cool slightly, then toss with mint and salt and pepper to taste. Serve warm or at room temperature.
Preparation Cook onion in butter in a 12-inch heavy skillet over medium heat, stirring occasionally, until softened, about 5 minutes. Add beets, water, and 1/2 teaspoon each of salt and pepper and simmer, covered, until beets are tender, about 20 minutes. Uncover and cook, stirring occasionally, until liquid has evaporated, 2 to 5 minutes. Cool slightly, then toss with mint and salt and pepper to taste. Serve warm or at room temperature.