I'm making a first attempt at tsimmis (or is it a "z") in my new slow cooker, which cooks hotter than my old one. I am thinking of the following:
peel yams and carrots, layer them into the crockpot with cut-up prunes, drizzle honey and cinammon over the whole mess, and cook on low overnight. I have a piece of stew-type beef to add -- do I cut it up and put it in the middle, or on top? Anything else that's missing? What about fried onions (would that help or hurt)?
I always make a vegetarian pareve tzimmes (I don't think there is a right or wrong spelling, except in the original Yiddish), so I am not an expert about the beef.
I believe you will also need to add some liquid to start, after you have piled in the veggies & beef. We use orange juice, enough to put about 1/2" of liquid in the bottom of the pot. In the fall, at Rosh Hashanah & Sukkot, I sometimes use apple cider instead of the o.j..
I also soak the prunes in boiling water, first. That is probably not necessary if you are using the "plump" prunes as opposed to the hard-as-rocks version that our grandmothers had available.
As far as the beef, I think you probably will want to brown it first, either cut into small chunks for ease of serving, or the whole piece, which could be placed on a platter with the tzimmes heaped around it for serving.
Good luck and have a zeisen Pesach!