Elegant Braised Lamb Shank Dinner

• 6 lb lamb shanks, 1 pound (455 g) each
• kosher salt, to taste
• freshly ground black pepper, to taste
• 2 tablespoons canola oil
• 2 medium carrots, minced, plus 1 pound (455 grams) oblique-cut
• 1 medium white onion, minced
• 2 stalks celery, minced
• 20 cloves garlic, minced, plus 15 whole, divided
• 2 tablespoons tomato paste
• 1 cup red wine
• 4 cups chicken stock
• 1 orange, juiced
• 1 lemon, juiced
• 5 sprigs fresh rosemary
• 10 sprigs fresh thyme
• 3 bay leaves
• 1 lb brussels sprouts, halved
• 1 lb red pearl onion, peeled
• olive oil, for drizzling
• 3 lb yukon gold potato, peeled, chopped, and boiled
• white pepper, to taste
• ½ cup unsalted butter, 1 stick, cubed and chilled
• 1 cup sour cream
• ½ cup heavy cream

Citrus Gremolata

• ¼ cup fresh parsley, chopped
• 1 lemon, zested
• ½ tablespoon flaky sea salt
• 2 cloves garlic, minced
• 2 tablespoons fresh chives, chopped
• 1 teaspoon horseradish
• orange, zested