In a large skillet, melt the butter over medium-high heat. Add the onions and cook, stirring, until soft, about 3 minutes. Add the tomato, scallion greens, and garlic and cook, stirring, for 30 seconds.
Remove the pan from the heat and add the vodka. Return to the heat and flame. When the flame dies out, add the fish stock. Bring to a boil and reduce by 50 percent in volume. Add the cream, salt, and pepper, and cook until reduced by 50 percent in volume.
Meanwhile, cook the pasta in a pot of boiling salted water until al dente. Drain in a colander.
Add the pasta to the cream sauce and toss to coat. Add the cheese, salmon, and herbs, and remove from the heat. Toss to coat. Serve immediately.
Yield: 2 servings