Bring water and rice to a boil in a saucepan over high heat. Reduce the heat to medium-low, cover, and simmer until rice is tender and liquid has been absorbed, 20 to 25 minutes.
Meanwhile, melt 1 tablespoon butter in a large skillet over medium heat. Cook and stir onion and garlic in melted butter until onion is translucent, 5 to 6 minutes. Add remaining 1 tablespoon butter and let melt. Stir in chili powder, paprika, cumin, black pepper, cayenne pepper, cloves, and nutmeg; cook, stirring often, for 2 more minutes.
Stir in black beans and tomato sauce, then bring to a simmer. Reduce the heat to low and cook until flavors blend, about 10 minutes. Remove from the heat and stir in cilantro. Let sit until cilantro wilts, about 5 minutes.
Fill warm tortillas with bean mixture and rice.
