Make chimichurri. To make Chimichurri: combine cilantro, parsley, oregano, red pepper flakes, garlic in a food processor. Chop until small and well combined. Add in red wine vinegar and olive oil. Season with salt and pepper. Refrigerate for at least 2 hours before using for best results. Thinly slice yellow onion. Melt butter in a pan over medium heat then add onion and cook for 15 minutes, stirring occasionally until starting to caramelize. Cut sausage into slices and cook in a pan until warmed through and browned. Cut cheese into cubes. To assemble bites: Place sausage on plate, layer with caramelized onions, top with cheese and then drizzle over chimichurri. If you want, put a toothpick through each one to hold them together.