1. Sprinkle chicken with salt and dredge in flour, shaking off excess.
2. Warm 1 Tbsp. butter and oil in a skillet over medium-high heat until butter foams. Add chicken; cook until cooked through and golden, turning once, about 8 minutes total. Transfer to a plate and cover with foil.
3. Add shallot to skillet and sauté until softened, about 1 minute. Add broth, orange juice, vinegar and sugar; cook, stirring, until slightly reduced, 1 to 2 minutes. Remove from heat, add remaining butter, and stir until thickened. Season with salt. Slice chicken, pour sauce on top and serve.