Heat oil in a skillet over medium-high heat. Saute onion until soft and translucent, about 5 minutes.
Meanwhile, sprinkle 1/4 teaspoon salt and thyme over chicken. Add chicken to the skillet. Saute chicken until no longer pink in the middle, 6 to 7 minutes per side. Transfer chicken to a serving plate and reduce heat to medium.
Add remaining salt, jam, vinegar, and pepper to the skillet. Stir constantly until jam melts, about 1 minutes. Spoon sauce over chicken and serve.
