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 mixture is smooth. Cook 1 minute, stirring constantly.

Add chicken broth and half and hald gradually to flour mixture; cook over medium heat, stirring contstantly, until mixture is thickened and bubbly.

Stir in pimiento, onion, salt, and hot sauce; cook over low heat, stirring constantly, until thoroughly heateds.