I buy the shanks at WF and they are usually one to 1.5 pounds. I do them in a clay cooker in the oven, but lots of folks get super results with electric slow cookers. Because of the small weight, they are falling off the bone tender in about two hours at 350 degrees F. I think for three pounds, I'd lower the temp and increase the time. Most recipes on the web are shank + veggies + something acidic. The acid can be anything from a small amount of vinegar to tomato sauce.
I've never eaten beef liver, but I've seen soaking it in milk suggested to mellow the flavor if you can tolerate dairy. Onions are often used with liver also (I use them with chicken livers) - I think the sweetness from carmelized onions mellows out the strong taste of the liver.