Heat oil in a Dutch oven over medium-high heat. Add leek to pan; sauté 2 minutes. Add broth, 1 cup water, and beer; bring to a boil. Add chopped carrot and next 8 ingredients (through bay leaves); return to a boil. Cover, reduce heat, and simmer for 15 minutes. Stir in lentils; cover and cook 30 minutes. Discard bay leaves.
Place 1 1/2 cups broth mixture in a blender. Remove the center piece of blender lid (to allow steam to escape); secure blender lid on blender. Place a clean towel over opening in blender lid (to avoid splatters). Blend until smooth. Return pureed mixture to pan, and stir in salt. Return mixture to a boil; cover, reduce heat, and simmer 10 minutes or until thoroughly heated, stirring occasionally.