Preheat the oven to 350 degrees F (175 degrees C).
In a small bowl, mix Monterey Jack cheese, diced onion, chopped cilantro, jalapeño pepper, and ground cumin. Season mixture with Salt and pepper to taste.
Cut a slit down the centre of each poblano pepper, being careful not to cut through. Stuff each pepper with the cheese mixture.
In a shallow dish, whisk together flour and eggs. In another shallow dish, add bread crumbs. Dip each pepper in the flour mixture, then the egg mixture, and coat with bread crumbs.
Heat vegetable oil in a large skillet over medium heat. Add stuffed peppers and cook until evenly browned, about 2 minutes per side.
Transfer peppers to a baking sheet and bake until cheese is melted and bubbly about 25 minutes.
Serve immediately with salsa and sour cream, if desired.
Enjoy!