Preheat your oven to 450°F (230°C). Allow the prime rib to sit at room temperature for about 1 hour before roasting.

In a small skillet over medium heat, toast the mustard seeds until they begin to pop, about 2-3 minutes. Remove from heat and let them cool slightly.

In a bowl, combine the toasted mustard seeds, chopped wild sage, minced garlic, olive oil, salt, and pepper. Mix well to form a paste.

Rub the mustard seed and sage mixture all over the prime rib, ensuring an even coating.

Place the prime rib on a roasting rack in a roasting pan, bone side down. Roast in the preheated oven for 20 minutes.

Reduce the oven temperature to 325°F (165°C) and continue roasting for about 1.5 to 2 hours, or until the internal temperature reaches your desired doneness (130°F for medium-rare).

While the prime rib is roasting, prepare the browned shallot butter. In a saucepan over medium heat, melt the unsalted butter. Add the finely chopped shallots and sauté until they are golden brown and fragrant, about 5-7 minutes.

Stir in the fresh thyme and lemon juice. Remove from heat and set aside.

Once the prime rib is done, remove it from the oven and allow it to rest for at least 20 minutes before slicing.

Serve the prime rib slices drizzled with the browned shallot butter.