Mustard Balsamic Baked Chicken

8 boneless chicken thighs;

1 tbsp. Dijon or homemade mustard;

1/4 cup of balsamic vinegar;

1/2 cup of olive oil;

2 tbsp. fresh lemon juice;

2 tbsp. fresh rosemary, minced;

1 garlic clove, minced;

Sea salt and freshly ground black pepper to taste;