1. Preheat the oven to 375°
2. For the spice rub, stir together the brown sugar, smoked paprika, cumin and chili powder in a medium bowl and set aside.
3. For the chimichurri, in a small bowl, stir together the red wine vinegar, chili, olive oil, garlic and shallot. Let sit for 10 minutes until the shallot has softened slightly then stir through the chopped parsley and oregano. Scoop out ¼ cup of the chimichurri to use to stuff the pork, reserving the rest to serve alongside the roast.
4. Trim the pork tenderloin of any silver skin and lay it on a large cutting board long side up. With a slicing knife, starting at the long side of the pork tenderloin begin to slice and open the meat making long sweeping cuts rolling open until it lays flat and even on the board about ½” thick.
5. With a spatula, spread ¼ cup of chimichurri evenly across the surface of the meat and then sprinkle with the feta pressing down with your hand to adhere. Roll back up the pork tenderloin so that the filling is enclosed in a tight spiral and rub all over the outside of the loin with the spice rub.
6. Place prosciutto on a clean surface slightly overlapping the slices lengthwise to form a row as long as the pork. Place pork close to the edge of the prosciutto and roll it up to enclose. Place pork in the centre of a large rimmed baking sheet prosciutto seam side down.
7. Cut the potatoes in half and place in a large bowl. Cut any large brussels sprouts in half, leaving the smaller ones whole. Toss the vegetables with the olive oil and season lightly with salt and pepper. Scatter the vegetables around the pork.
8. Bake for 25 to 27 minutes or until the internal temperature of the pork is 145° Let rest for 12 minutes before slicing the pork on a cutting board into inch thick slices. Serve the sliced pork along with the vegetables and the extra chimichurri for drizzling.