Prepare the marinade in a blender. Smash the olive oil, the mustard, the garlic and the fresh herbs. Add the meat, salt and pepper it and then marinate it. Place it in a tray and rinse it with the broth. IT is ready for cooking. Cover it with wrapping paper and seal it. Bake in 160ºc for at least 2.5 hours.
In a pot add the fresh onion, the garlic, and the orzo and sauté. Then pour 300 ml of pork broth and 2 lt of vegetable broth. Cook for 15 minutes and stir often. At the end add the tomatoes in cubes, the lemon juice, and the chopped basil. Cook for 1 more minute.
Add the remaining broth in a pot and mix it with corn flour in order to make a thick sauce. Serve the youvetsi with grated gruyere cheese. Cut the meat in thick slices and add the sauce on top.
Tip: If the sauce is thick in texture, just add 50gr of vegetable broth.