Preheat oven to 400°F. Line a large baking sheet with parchment paper.
Heat olive oil in a large skillet over medium-high heat. Add cumin seeds and toast for 30 seconds until fragrant.
Stir in curry powder, turmeric, and garlic; cook for another 30 seconds until the mixture is aromatic but not browned.
Add cauliflower florets to the skillet along with salt and pepper. Cook without stirring for 2 minutes to let them develop color, then stir occasionally as they cook until golden and tender-crisp, about 8-10 minutes total.
Pour in heavy cream and bring to a gentle simmer. Season with an additional pinch of salt if needed, then set aside on the stovetop.
Pat fish fillets dry with paper towels and season both sides with salt and pepper. Heat olive oil in a large nonstick skillet over medium-high heat until shimmering.
Add fish to the hot skillet, skin-side down if applicable. Cook without moving for 3-4 minutes until golden and easily releasing from the pan. Flip and cook another 2-3 minutes until internal temperature reaches 145°F and flakes with a fork.
Place each fillet on top of a generous portion of curried cauliflower, spooning extra sauce over the fish as you serve.