This started as one of those "what on earth can I make with what I have on hand?" meals. But my goodness, it's delicious, and super healthy--four vegan food groups, lots of fiber, and even a good calcium count. It could be very low fat or even non-fat if you wanted it to be. You should make it. Even though it currently bears no resemblance at all to enchiladas. Lots and lots of room for modifications in here (I'd love to somehow turn it into a casserole with corn tortillas after all...), but here's what I did:
Put on brown rice to cook. Millet would be fantastic too.
Chop a medium-sized peeled sweet potato (I used the orange "yam" kind, but the mealy yellow ones would be just as tasty) into half-inch dice. Chop half of a large onion in similar pieces. Toss with canola oil (optional, depending on what kind of pan you use) and roast in a 400-degree oven, turning occasionally, about 30 minutes or until soft. Reserve the rest of the onion.
Start roasting 4-5 cloves un-peeled garlic in a non-Teflon pan, turning occasionally.
If you're not using pre-made enchilada sauce, toast some spices to make your own. I make no claims to authenticity here, but my memory and taste buds told me to do about a half-teaspoon each whole cumin and black mustard seed, which I ground and then added a good teaspoon of dried (not ground, yet) oregano. Set aside roughly a third of this mixture. If you are using pre-made sauce, just make a smaller amount of this blend.
When your garlic is soft, add it to the two-thirds portion of the spices, add dried hot chili to taste, and grind that all up. I put it in a miniature food processor, added a few tablespoons of the tomatoes I'm about to mention, and whizzed it until smooth. If you're still working in a mortar there'd be no reason to involve tomatoes in this step.
Mince the remaining half of your onion. Add half of the mince to a skillet with a tablespoon or two of olive oil. Saute until soft. Add your spice blend and a 14-oz. can of chopped or ground tomatoes. I used fire-roasted ones. You should too, if you can. I also found the sauce intense and thick enough that I wanted to add about 1/3 cup water. Salt if you want, but I didn't need to. Leave on very low while you finish the rest of the goodness.
Fire up one more skillet and use it to saute the remaining 1/4 of an onion (which should be minced by now). When mostly soft, add a drained can (14 oz.) of black beans and a cup or two of pre-cooked collards or similar greens along with your remaining spice blend. Let that simmer together for a bit to blend the flavors and make sure the collards are cooked enough.
When the rice and sweet potatoes are ready, put it all together: bed of rice, then beans & greens, then sweet potatoes & onions, and then sauce. This would be fantastic with toasted pepitas and/or fresh cilantro, raw sweet onion, avocado, etc.