1. Trim fat from lamb shanks. Place beans and next 4 ingredients (through garlic) in a 7-quart electric slow cooker; stir well. Place lamb shanks on bean mixture; sprinkle with tarragon, salt, and pepper. Pour tomatoes over lamb. Cover and cook on HIGH for 1 hour. Reduce heat to LOW, and cook 9 hours or until lamb is very tender.
2. Remove lamb shanks from slow cooker. Pour bean mixture through a colander or sieve over a bowl, reserving liquid. Let liquid stand 5 minutes; skim fat from surface of liquid. Return bean mixture to liquid. Remove lamb from bones; discard bones. Serve lamb with bean mixture.
Nutrition Tip: Canned beans are a convenient option when you don't have time to prepare dried beans--the drawback is the sodium content. Reduce the sodium content of any variety of canned beans by 40 percent simply by draining and rinsing them.