1. If using beets, preheat oven to 400 degrees F. Cut greens from beets, leaving about 1 inch of stem attached; reserve about 8 cups greens, lightly packed. Wash and dry the beets. Wrap in foil and roast until tender, 1 1/4 to 1 1/2 hours, depending on the size. (Alternatively, place beets in a microwave-safe dish, add 1/4 cup water, cover and microwave on high for 20 to 25 minutes.) When the beets are cool enough to handle, peel 4 of them and cut into 1/2-inch wedges. You should have about 2 cups. Place in a medium bowl. (Reserve the remaining beets for another use.)
2. Using a mortar and pestle or the side of a chef's knife, mash garlic and salt into a paste. Transfer to a large bowl. Add vinegar and whisk to blend. Add oil, oregano and pepper, whisking until blended. Measure out 1 tablespoon and add to the beet wedges; toss to coat. Add beans to the remaining dressing and toss to coat. Let marinate at room temperature until ready to use.
3. Place onion in a small bowl, cover with cold water and add a handful of ice cubes; let stand for 10 minutes, or until ready to use.
4. Meanwhile, bring 2 cups lightly salted water to a boil in a large wide pan. Wash beet greens in several changes of water; trim the stems. Add the greens to boiling water, cover and cook until tender, about 5 minutes. Drain well, pressing on the greens with the back of a spoon to remove excess moisture. Cut into 1-inch pieces.
5. Drain the onion. Add to the beans along with greens; toss to coat. Spoon the salad onto a serving platter or individual plates and garnish with the beets, if using. Serve immediately.

Yield: 4 servings