Wash and dry the poblano peppers, then arrange them on a foil-lined baking sheet. Broil the peppers for 10 minutes, flip them over, and broil for another 8 minutes until charred. Transfer the peppers to a plastic bag to sweat for about 20 minutes, which helps loosen the skins. Once cool enough to handle, carefully peel off the skins. Make a slit in each pepper and scoop out the seeds, discarding them. Take care not to tear the peppers, as you'll need them whole for stuffing.

Heat a skillet over medium heat and add the ground beef. Use a spatula to break up and crumble the meat. When the beef is halfway cooked, add the diced onion and minced garlic. Season with salt and black pepper to taste. Continue cooking until the beef is fully cooked through. Stir in the drained corn and cook for another minute. Transfer the beef and corn mixture to a large bowl, leaving about a tablespoon of grease in the skillet. Add the chopped cilantro to the bowl and mix well. Allow the mixture to cool for a few minutes before stirring in the shredded mozzarella cheese. I like to let the filling cool a bit so the cheese doesn't melt instantly but creates a creamy texture once stuffed inside the peppers.

Carefully stuff each peeled and cored poblano pepper (from Step 1) with the prepared ground beef filling (from Step 2). Be gentle to avoid tearing the peppers. Once stuffed, set the peppers aside while you prepare the salsa.

Cut the roma tomatoes into chunks and add them to a blender. Add the serrano pepper, 1/4 medium white onion, garlic clove, ground cumin, chicken bouillon, and Mexican oregano. Blend for a couple of minutes until completely smooth. In the same skillet with the reserved grease, heat the blended salsa over medium heat, cooking for several minutes to develop its flavor. I like to simmer the salsa for at least 5 minutes to mellow out the raw onion and garlic.

Gently nestle the stuffed peppers (from Step 3) into the skillet with the simmering salsa (from Step 4). Cover and cook over medium heat for about 10 minutes, or until the cheese inside is melted and the peppers are heated through. Once done, serve the peppers with plenty of salsa spooned over the top and enjoy!