In a blender, combine orange quarters, orange juice, garlic, smoked paprika, olive oil, and salt. Blend until smooth, then coat the pork with the marinade. Refrigerate for 8 to 24 hours.

Allow the marinated pork to sit at room temperature for 1 hour. In a saucepan, combine orange zest, orange juice, marmalade, brown sugar, rosemary, and cinnamon. Simmer for about 10 minutes.

Preheat your oven to 450°F. Place the marinated pork on a baking sheet and sear in the hot oven for 5 minutes.

Toss the halved potatoes and Brussels sprouts with olive oil, salt, and pepper. Scatter around the pork, lower the oven temperature to 350°F, and cook for an additional 10 minutes.

Brush the pork with the orange glaze, then bake for another 10 to 15 minutes until the internal temperature reaches 145°F.

Let the pork rest for 15 minutes, then slice into medallions and serve with the remaining sauce drizzled on top.