Preheat the oven to 400 degrees F.
Cut your peppers in half down the top, middle, so that you are splitting the stem down the middle. Scrape out the insides. Take this time to also dice your onions and mince your garlic cloves.
Arrange the pepper halves cut side up on a lined baking tray. Sprinkle with salt and pepper and drizzle with 2 tbs olive oil. Roast the peppers in the pre-heated oven until they are tender about 12-15 minutes. Once done, set aside.
While the peppers are cooking, heat the remaining 1 tbs of olive oil in the bottom of a large pot over medium high heat. When the oil is hot, add the ground beef, sprinke with salt and pepper and cook through (5-8 minutes). Be sure to break up the meat into small bits as it cooks.
While the meat is cooking, prepare your couscous according to package instructions. Set aside when the couscous is ready.
When the meat is done cooking, remove it with a slotted spoon from the pan and set aside. Add the onions, garlic, cumin and chili powder to the pot along with a sprinkle of salt and pepper. Stir and cook for around 6 minutes. Add the tomatoes to the pot and simmer until the tomatoes start to fall apart and the mixture begins to thicken (about 12-15 minutes). Add the ground beef back to the pot along with the drained black beans and apple cider vinegar. Then remove from heat.
Fill each roasted pepper about halfway with the cooked couscous. Divide the meat/tomatoe mixture among the peppers and top each pepper/couscous with it. Sprinkle the shredded cheese on top of the peppers and put back in the oven for a final 20 minutes.