There is perhaps no better way to prepare a beef stew than with a long, slow simmer. The low, moist heat slowly breaks down the structure of the muscle tissue, tenderizing the meat. You just can't get that by rushing things. Here, contributing writer Ken Haedrich offers his basic stew recipe, but he notes that, like so many slow-cooker dishes, it readily accepts additions and adjustments. "For instance, I sometimes use a cup of dry red wine in place of the beef stock. And I'll often add a handful of dry lentils, perhaps one third cup, at the outset as well. If you like, you can use a sliced parsnip too. There are plenty of ways to play with the basic formula. Just let it simmer all day long. Unmentionably good."
Put everything but the flour and the tomato paste in a slow cooker; stir to combine.
Cover and cook on the low setting for 8 to 9 hours or on high for 4 to 5, until the beef is tender and the potatoes are just fork tender.
Stir the stew once or twice as it cooks, if possible. About 30 minutes before serving, transfer a ladleful of the broth to a small mixing bowl.
Add the flour and tomato paste and whisk until smooth. Stir the mixture into the stew and cook for the remaining half hour. Makes 6 to 8 servings.