Place pimiento in container of an electric blender, and process until smooth, stopping once to scrape down sides. Set pimiento aside.
Melt butter in a heavy saucepan over low heat; add flour, and stir until flour mixture is smooth. Cook 1 minute, stirring constantly.
Add chicken broth and half-and-half gradually to flour mixture, and cook over medium heat, stirring constantly, until broth mixture is thickened and bubbly.
Stir in pimiento, onion, salt, and hot sauce; cook over low heat, stirring constantly, until thoroughly heated.
Note: You can easily double the recipe to serve 8.