Well, we had a sirloin tip roast for dinner Sunday. I roasted it in the oven, not a crockpot but still had leftovers. So I made the difficult decision to make soup, rather than have the leftover roast beef and gravy (although I did keep a few slices for a lunch this week). I didn't have enough, so I seared a few soup bones and slow cooked them for some more meat.

I tried doing the tomato paste as you recommended and it is an improvement. It isn't so much that it is sweeter as much as it is that the taste is a little less acidic / tomatoey (is that a word?). It gives it a little more of a hearty taste. Very subtle but an improvement nonetheless.

Thanks for the tip rb!!