*Note: Halibut fillets should be about 1/2-in. thick. Make fish stock by simmering 1 to 2 pounds heads and bones of white-fleshed fish only in 2 to 3 quarts of water about 2 hours. Add water as needed. Strain stock into large kettle. Add clam juice, beer, carrots, celery, garlic, leek and saffron. Bring to boil, reduce heat and simmer until carrots are crisp-tender. Combine cornstarch with 1/2 cup wine and stir into simmering sauce. Simmer 5 minutes, then season to taste with salt, white pepper, hot pepper sauce and MSG. Add lobster tails, shrimp (that have been split down back and sand vein removed), scallops, clams and halibut. Add remaining 1 1/2 cups wine. Bring to boil and boil 8 to 10 minutes or until lobster is done and clams open. Serve in large bowls with generous amounts of liquid. Serve garlic toast or hot crisp sourdough bread slices with Bouillabaisse, if desired.