Season the salmon fillets with curry powder, kosher salt, and black pepper. Roast in a 400°F oven for about 15 minutes, until just cooked through. Remove from the oven and set aside.
In a large skillet, melt the butter and sauté the onion until softened. Add the garlic, ginger, and curry paste and cook until fragrant, about 2–3 minutes. Stir in the coconut milk, tamari, and fish sauce and whisk to combine. Add the broccoli and simmer until tender, about 10–15 minutes.
Reduce the heat and add the roasted salmon to the sauce for a few minutes to warm through. Serve over noodles and enjoy.