Drain and rinse all liquid off beans. Combine beans in a bowl and set aside. Begin cooking bacon in a saute pan. Begin roasting yams in preheated oven until soft, and remove to let cool enough to handle.
Heat olive oil in another large saute pan for the lamb. Season the rack of lamb with salt and pepper. Place lamb into hot pan and sear meat all around.
Remove bacon to drain on paper toweling. In same pan lightly saute onion and garlic in bacon fat until translucent. Add red wine and reduce by half.
Place the lamb in a roasting pan and roast in the oven until done to your liking, about 15 to 20 minutes for medium rare, an internal temperature of 125 degrees F (this means that because of the 5 to 8 minutes of carryover cooking while it rests, you pull it out at 120 degrees F so it will end up at 125 degrees F for medium rare).
When yams are cool enough to handle, peel off skin and add butter and cream and mash. Season with salt and pepper, as needed.
Remove the lamb to a utility platter and let rest before slicing.
Add demi-glace and tomato paste to the pan with the onion, garlic, and bacon fat, then incorporate all beans with mixture. Lower heat and simmer. Add rosemary and chives. Season with salt and pepper, to taste.
Place sweet potatoes in the middle of a serving platter. Surround potatoes with bean ragout. Slice rack of lamb in between bones and lay over potatoes. Spoon demi-glace sauce over and serve.