You know, I don't think you need to overthink this too much. If you look at a typical Indian curry recipe, it might have 10 spices in it. Just leave out the cumin, and maybe bump up the other spices a little to compensate. It won't be exactly the same, but it will still be delicious. You are correct that you'll have to be careful to avoid pre-packaged spice mixtures unless the ingredients are spelled out. Here is my Chana Mushroom Masala, from which you can safely omit the cumin: http://www.herbivoracious.com/2009/09/quick-chana-mushroom-masala-chickpea-curry-recipe.html
If Belgian food is anything like the Dutch food my Oma made, your best bet is to limit it to the dessert course and strike out in a different direction. Even there, throwing in an extra pinch of salt and a little fresh ginger or cardamom powder may help liven it up for your friends.
One area where you'll both be happy: Mediterranean/Middle-Eastern fare. If you pick a recipe with plenty of aromatic herbs and spices, and maybe yogurt, it'll have the rich flavors your friends are used to. However, they won't be the same dishes they have at home, so they can't compare unfavorably to their mom or auntie's cooking. Flatbreads, kebabs, braised lamb, goat, yogurt sauces... these will be familiar elements, but by using Mediterranean or Middle-Eastern versions, you'll give them a taste of the exotic too.
Using South or Central American cuisine will have similar results; dishes rich in pungent chilis, cumin, and coriander will combine elements of comfort food with something new. Indian chapatis and naan (flatbreads) are very similar to homemade tortillas. It goes without saying that beef is to be avoided. Depending on what part of India your guests are from, coconut milk and tamarind paste may be other familiar elements to play with.
Portugal also has a fine tradition of spicy foods, including the Vin d'alho which Indian adapted into the now-familiar vindaloo.
If you don't feel comfortable with these cuisines, you might do Indian, but with a fusion twist. I found that Saag Paneer with blocks of feta instead of paneer is absolutely divine. Halloumi cheese might work well too. In fact, I'd say it's better than the original dish.
A word on dietary restrictions:
Presumably you know your friends' dietary needs, but if they're bringing new acquaintances it is wise to give some thought to dietary restrictions. Many Indians are Hindus, who do not eat beef, and another major fraction are Muslim. Muslims follow a dietary law called halal, which is very similar to kosher law, and likewise excludes pork and animal blood. It also excludes alcohol... which means a spicy tamarind-port pork marinade isn't viable.
A sizable part of the Indian population is also vegetarian, so any meal should include a vegetarian entree.
Best Answer
Apparently a lot has changed since this question was first posted exactly five years ago today.
Today a simple Google search yields many recipes, a lot of lore, and lots of pictures.
Here's one picture I like from DamnFineLife:
But, I suspect that one has been very much prettied up for the camera.
This one is from the blog Fit Foodie Megha, which does restaurant reviews. The chicken was prepared by a well known and apparently very highly regarded restaurant called Punjab Grill in Phoenix Market City, Pune, Maharashtra, India.
Here is an example from the blog Chandigarh Chaat showing perhaps the original variation from Kotkapura, near the Indian border with Pakistan.
Finally, here is one from the entertainment blog alvinology:
That one was prepared one year ago by the world class chef Hemant Oberoi, who the blogger credits with making Atta Chicken famous beyond Kotkapura. Not coincidentally, it is Chef Oberoi who the OP learned about on NPR and inspired the question here.
For more images, click here
For recipes, click here
I watched the videos and read the recipes. The original Kotkapura recipe is still a closely guarded secret, but a number of foodies have published their take on it.
To paraphrase: Take a clean chicken and score it (or not) on the breast and thigh. Other recipes say prick the chicken with a fork. Marinate it in a heavily spiced (usually yogurt based) marinade for hours. Some recipes do that in two steps, one in a dairy based marinade, the other in an oil based one.
Stuff the chicken cavity with some combination of almonds and/or pistachios and whole garlic cloves.
Wrap the chicken tightly in muslin, cheesecloth, or in at least one recipe, banana leaves. Although in the banana leaf recipe, the cooking method is quite a departure from the others.
Make a simple dough with just whole wheat (atta) flour and water, perhaps salt.
Completely encase the chicken with at least a 2 centimeter layer of the dough, carefully sealing (that's critical).
Now cook it in a tandoor (which is the Kotkapura method) for at least two hours or until the dough is completely charred. You can also do it in a barbecue or a very hot oven for approximately three hours, again until the dough is completely charred. Three hours seems like a long time at such high heat, but if you watch the videos or read the blogs, they all seem to agree that long and hot is the way to go.
When it is done, don't break it until you are ready to eat it. Supposedly it can be kept at room temperature for three days if it hasn't been broken into. I am more than a bit skeptical about that, but I'm just repeating what I've read. Refrigerated and unbroken, the chicken is supposed to be good for up to two weeks. Just rewarm it, then break into it. Discard the cooked dough.
The chicken supposedly divine, and very, very juicy.
If you found this information interesting, you might also enjoy watching this video, which is very coy about the super-secret Kotkapura recipe, but shows a lot of the fun stuff including breaking into the chicken.