Cut the tops and bottoms off the beets . . .
Wrap in aluminum foil and bake for an hour at 350°F . . .
Remove from the oven and let them sit for a bit until they have cooled enough to handle. Unwrap under running water and rub them to peel the skin off; it'll fall off without effort . . .
Slice them in thin rounds. Slice an onion into rings and alternate stacking slices of beets and onions into your serving bowl. Add extra virgin olive oil, vinegar (lately I've been using white balsamic vinegar), salt and pepper.