How to Make It
Cook lobster tails in boiling salted water to cover 3 minutes or until opaque in center; drain and cool slightly. Using kitchen shears or a sharp knife, split tails lengthwise. Remove meat, and cut into 1/2" pieces. Set meat aside, and reserve shells.
Heat oil in a large saucepan over medium-high heat. Add onion and garlic; sauté 4 minutes or until tender. Add tomato paste; cook 1 minute. Remove pan from heat; stir in Cognac. Add water and reserved lobster shells; bring to a boil. Cover, reduce heat, and simmer 30 minutes. Pour broth through a wire-mesh strainer into a large measuring cup or bowl, discarding shells.
Melt butter in a large skillet over medium heat; whisk in flour until smooth. Cook 1 minute, whisking constantly. Gradually whisk in lobster stock, whipping cream, and vanilla bean seeds; bring to a boil. Reduce heat, and simmer 15 minutes or until sauce reduces to 2 cups. Stir in salt, tarragon, and chopped lobster meat. Keep warm until ready to serve.
*Substitute 1/2 tsp. vanilla extract, if desired.
Note: Here's a tip to make the most of your vanilla bean flavor--measure the whipping cream for this sauce and gently scrape vanilla bean seeds into the whipping cream using the tip of a paring knife. Plop the vanilla bean pod into the whipping cream and let stand while preparing the lobster stock. Remove pod before pouring cream and seeds into stock.
Christmas with Southern Living 2008