In a medium saucepan place the chicken stock, butter, and the first quarter teaspoon of salt. Bring the liquid to a boil and then remove the pan from the heat. Add the couscous, cover the pan, and let it sit for 5 minutes. Transfer the couscous to a glass bowl and let it cool.
In a small bowl place the basil, garlic, olive oil, and the second quarter teaspoon of salt. Mix the ingredients together and set the sauce aside.
In a large saucepot place 10 cm of water and bring it to a boil over high heat. Add the lobsters and let them cool.
Remove the lobster meat from the tails and claws. Remove and discard the intestinal tract from each tail. Cut the lobster meat into half inche pieces.
In a medium bowl place the lobster pieces and 6 tablespoons of the basil-oil mixture. Toss the ingredients together so that the lobster is well coated. Set it aside.
In another medium bowl place the cooled couscous, tomatoes, cucumbers, lemon juice, and the remainder of the basil-oil mixture. Toss the ingredients together well to make the tabbouleh.
In the center of each of 4 individual serving plate place a mound of the tabbouleh. Arrange the lobster pieces around the edge.