Denzelmum did you use whole urad dahl? I have thought about cooking this recipe but only have split urad dahl at present, not that it would probably matter, I guess. My son really likes black lentils. This is one of the recipes I've made with them, but not in the TMX yet, :
http://indianfood.about.com/od/vegetarianrecipes/r/kaalidaal.htm (I can't bring myself to add cream and oil and ghee though! Just add a slurp of cream and whisk in some ghee)
Incidentally Jacob (son) says that in India, dal is usually quite soupy and I have found that many, more traditional, recipes are like that. I often add less water, or cook longer to evaporate more liquid to make it thicker. We quite like the dry lentil curry recipe in the indian cookbook, which is thicker too.
I really recommend this website as a great source of Indian vegetarian information and recipes, the videos are great!, many would be very easy to convert to TMX. I put up a chick pea and spinach curry conversion (chole palak) on this forum, which I directly converted from there.
http://www.manjulaskitchen.com