Preheat oven to 350 degrees F. Thoroughly coat a large baking sheet with cooking spray.
In the bowl of a food processor, combine beans and roasted red peppers. Pulse until chopped, but not smoothly pureed.
Transfer the mixture to a medium-sized bowl and stir in grated onion, garlic, parsley, oregano, egg, breadcrumbs, salt and pepper until well combined.
Using a rounded 2 tablespoon portion of the bean mixture, form “meatballs” by rolling between the palms of your hands. Place the “meatballs” on the prepared baking sheet, spacing evenly.
Bake until the meatballs are firm to the touch and have developed a light golden brown coating, 15 to 20 minutes.
In a large saucepan, heat your favorite marinara sauce over medium heat until simmering. Add “meatballs” and stir to coat.
Simmer until the sauce thickens slightly, stirring occasionally, 10 to 15 minutes. Serve over spaghetti.