Orange and Balsamic Chicken Breasts

1 1/2 lb. boneless, skinless chicken breast, pounded to 1/2 in. thickness
salt
1/4 C. all-purpose flour
2 Tbsp. unsalted butter
1 Tbsp. vegetable oil
1 shallot, finely chopped
1/3 C. chicken broth
1/3 C. orange juice
1 Tbsp. balsamic vinegar
1 tsp. sugar

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