I should say that we can't eat sugar or chili powder or any kind of peppers other than black pepper. Also, can't do vinegar, except for apple cider, or wine. Love the fennel thing - I do it a lot for pork.
I assume theres cayenne and/or other types of chile pepper in chili powder, so I don't know if you can use it or not... But I like mixing equal amounts of chili powder, paprika, and plain sugar as a base and go from there.
I recently did some short ribs with an Asian slant. The dry components were Chinese five spice, cumin, ground ginger and dang if I can remember the rest. Browned well and into the slow cooker with Xiao Xing (?sp) wine, black vinegar and sesame oil. Really tasty.