Place chicken in a 3- or 6-qt. electric pressure cooker; top with onion. In a small bowl, whisk 3/4 cup broth, paprika, tomato paste, garlic, salt, thyme and hot pepper sauce; pour over chicken., Lock lid; close pressure-release valve. Adjust to pressure-cook on high for 15 minutes. Let pressure release naturally for 10 minutes; quick-release any remaining pressure. A thermometer inserted into chicken should read at least 165°., Remove chicken; keep warm. In a small bowl, whisk flour and remaining 1/4 cup broth until smooth; stir into pressure cooker. Select saute setting and adjust for low heat. Simmer, stirring constantly, until sauce is thickened and slightly reduced, 8-10 minutes. Press cancel; stir in sour cream. Serve with chicken.