- Make the celery root purée: Place celery root and thyme in a medium pot and cover with heavy cream. Bring to a simmer. Cook until tender, about 25 minutes. Strain celery root through a sieve, reserving cream. Transfer cooked celery root to a blender with garlic cloves and purée until smooth, adding heavy cream as needed—about 2 cups. Stir in butter and season to taste. Pass celery root purée through a tamis sieve and reserve.
- Make the carrots: Bring a medium pot of heavily salted water to a boil. While water is heating, prepare an ice bath. Blanch carrots until tender, about 2 minutes. Transfer immediately to ice bath until chilled through. Remove and drain on paper towels.
- Make the bison: Prepare a wood fire to grill over, or preheat grill to high heat. Brush bison with oil and season with salt and pepper. Grill for about 4 minutes, then flip and cook until medium-rare, about 2 to 3 more minutes. Remove from grill and allow to rest for 4 to 5 minutes.
- In a large cast-iron pan, heat oil over medium-high heat. Add carrots and cook until browned, then add butter and season to taste with salt and pepper. Remove from pan and drain on paper towel-lined plate.
- Spoon a large tablespoon of celery root purée into four large bowls. Place carrots on top. Slice bison steaks in half and season lightly with good sea salt. Place atop carrots. Drizzle with olive oil around plates and serve immediately.