- Position rack in center of oven; preheat to 400 degrees F. Sprinkle ribs with salt and pepper. Wrap each rib rack tightly in heavy-duty foil; set on rimmed baking sheet. Bake ribs 45 minutes. Cool slightly. Unwrap; drain juices. Cut into individual ribs.
- Meanwhile, heat oil in heavy medium saucepan over medium heat. Add onion and saute until tender, about 10 minutes. Add garlic and saute 1 minute. Add tomato puree and next 3 ingredients. Bring to boil. Reduce heat to low and simmer until sauce thickens slightly, about 20 minutes. Stir in vinegar. Season sauce to taste with salt and pepper.
- DO-AHEAD TIP: Ribs may be made 1 day ahead. Sauce may be made 1 week ahead. Cool ribs and sauce. Cover separately and refrigerate.
- Line same baking sheet with foil. Dip ribs into sauce. Place ribs, meaty side up, on sheet. Roast 15 minutes. Dip into sauce again. Roast until meat is very tender, about 20 minutes.
- MAPLE BAKED BEANS: Combine 8 cups water, beans and salt in heavy large pot or Dutch oven. Simmer uncovered until beans are almost tender, about 30 minutes. Drain.
- Saute bacon in same pot over medium heat until crisp, about 6 minutes. Transfer bacon to paper towel-lined plate. Add onion and saute over medium-high heat until tender, about 5 minutes. Add 1 cup water, maple syrup, ketchup, vinegar, drained beans and reserved bacon. Simmer uncovered until mixture thickens slightly, stirring occasionally, about 30 minutes. Season beans to taste with salt and pepper.
- DO-AHEAD TIP:Beans can be made 2 days ahead. Cool. Cover and refrigerate. Rewarm before serving.