Preheat your oven to 450°F (230°C). Rub the prime rib with olive oil, kosher salt, black pepper, and crushed green cardamom pods. Make sure to coat the meat evenly. Place the prime rib on a rack in a roasting pan, fat side up.

Roast the prime rib in the preheated oven for 20 minutes. Reduce the oven temperature to 325°F (160°C) and continue roasting until the internal temperature reaches 130°F (54°C) for medium-rare, about 1.5 to 2 hours depending on the size of the roast. Remove from the oven and let the meat rest for 20-30 minutes before slicing.

While the prime rib rests, heat a skillet over medium-high heat. Add a splash of olive oil and the halved shallots, cut side down. Sear until they are charred and caramelized, about 5-7 minutes. Remove from heat and set aside.

In a saucepan, combine the tamarind paste, brown sugar, soy sauce, and balsamic vinegar. Cook over medium heat until the mixture thickens and reduces by half, about 10-15 minutes. Stir occasionally to avoid burning.

In a separate saucepan, melt the unsalted butter over medium heat. Continue cooking until the butter turns golden brown and has a nutty aroma, about 5-7 minutes. Add the chopped walnuts and cook for an additional 2-3 minutes, stirring frequently to coat. Remove from heat.

Slice the rested prime rib and arrange it on a serving platter. Drizzle the tamarind reduction over the slices. Top with charred shallots and spoon the brown butter and walnut confit over the dish. Garnish with fresh parsley before serving.