Preparation Heat olive oil in heavy medium saucepan over medium heat. Add chopped red onion and beet cubes. Cook until onion is tender but not brown, stirring frequently, about 8 minutes. Add 1/2 cup water. Increase heat to high and boil until mixture is thick, about 5 minutes. Add vinegar, raisins, sugar, ginger, mustard seeds, and pinch of cumin seeds. Reduce heat to medium-low and simmer until beet cubes are tender and chutney is thick, stirring often, about 8 minutes. Season to taste with salt and pepper. Cool. DO AHEAD: Can be made 1 week ahead. Cover and chill.