Melt butter in a small saucepan over low heat; add flour, stirring well. Cook 1 minute, stirring constantly. Gradually add milk; cook over medium heat, stirring constantly, until thickened and bubbly. Add mustard, hot sauce, and salt; stir until smooth. Stir in ham, cheese, tomatoes, and green pepper.
Pour mixture into a lightly greased 1-quart casserole. Bake at 350° for 1 hour. Serve over toast points or hot cooked rice.