1. Melt the butter in a medium stockpot set over medium-low heat. Add the shallots, the leeks, the onions, and the scallions. Cover, and cook, stirring occasionally, until softened, about 20 minutes. Add 4 cups chicken stock, and stir well.

2. Add the lettuce, and cook, covered, until the lettuce has wilted, about 10 minutes. Add snipped chives, dill, tarragon, and parsley; cook, covered, until very aromatic, about 10 minutes more.

3. Fill the jar of a blender halfway full with mixture; blend until well combined but some texture remains, being careful not to puree. Transfer soup to a large bowl; blend remaining mixture. Rinse out the stockpot.

4. Return soup to stockpot, and set over medium heat. Stir in the remaining 8 cups stock; season with salt and pepper. Cook until heated throughout. Before serving, garnish with dill, tarragon, and the julienned lettuce.