Preheat the oven to 250 F (120 C).
Wash the oranges and lemon, then zest them.
Squeeze the juice. Set aside.

Brown the rôti in a casserole, on all sides, with half of the butter, oil, and two cloves of garlic.
Discard the cooking fat and set the rôti aside on a plate.
Add the other half of the butter and the shallots, and cook without browning.
Replace the rôti in the casserole with the citrus juice, some orange zest, wine, and thyme.
Season with salt and pepper, bring to a simmer, cover, and bake for 2 hours.

Blanch the remaining zest for 2 minutes. Refresh and pat dry.
Mix with the remaining minced garlic, two tablespoons of butter, and parsley.
Heat for 2 minutes in the microwave when serving.

Once the pork rôti is cooked, remove it from the casserole and coat it with the gremolata, and serve with the cooking juice in a sauceboat.