In a saucepan over medium-high heat, add the oil. Stir in the diced onion and sauté for 5 minutes, until the onion is translucent. Stir in the chopped jalapeno pepper, and cook for another minute. Stir in the garlic and cook for 30 seconds. Stir in the black beans, tomatoes, orange juice, spices and water. Cover, reduce heat to low and cook for about 25 minutes, stirring occasionally. If the mixture seems too thick, add a bit more water. Stir in the cilantro and season with salt and pepper. Let the mixture cool down for 15 minutes.
Preheat the oven to 425F
Line two baking sheets with parchment paper. Arrange 4 corn tortillas per sheet. Spread about ⅓ of a cup of black bean filling on top of the corn tortilla, leaving about a ½ inch border. Top each with shredded cheddar. Bake for 5 minutes, then rotate pans from bottom to top, and bake another 5 minutes. Serve with guacamole, salsa, sour cream and extra cilantro, if you like. Leftover black beans keep well in the fridge for up to 5 days, or can be frozen for up to 1 month. Makes 8 tostadas.