Preheat oven to 375°.
Remove root and 1 inch stem on beets; scrub with a brush. Cut beets in half; place beets in a 13 x 9-inch baking dish. Add water. Cover with foil, and bake at 375° for 1 hour or until tender. Cool; rub off skins. Cut beets into 1/2-inch slices.
Combine rind and next 6 ingredients (through pepper) in a small bowl. Toss half of juice mixture with beets.
Cut avocado in half lengthwise. Slice each half into 12 slices. Place watercress on a platter; top with beets, orange sections, onion, and avocado. Drizzle remaining juice mixture over salad, and top with pecans. Serve immediately.