Chicken Thighs with Sweet Red Onions and Balsamic Vinegar

2 tsp EVO oil
1 pound red onion, cut into (1/2-inch-thick) slices and separated into rings (about 3 medium)
1/2tsp coarsely ground black pepper, divided
1/4tsp salt, divided
4 (6-oz) chicken thighs, skinned
1/4tsp dried oregano
1/4tsp dried marjoram
4 tsp balsamic vinegar, divided (see below)
2 tbsp chopped fresh flat-leaf parsley
4 lemon wedges

The chicken is smothered in a thick onion sauce. Serve it over mashed potatoes. Heat the oil in a large nonstick skillet over medium heat. Add the onion, 1/4 teaspoon pepper, and 1/8 teaspoon salt. then sauté for 5 minutes. Add 1/4 teaspoon pepper, 1/8 teaspoon salt, chicken, oregano, and marjoram to pan, and sprinkle with 3 teaspoons of vinegar. Cover, reduce heat, and simmer 25 minutes or until chicken is done. Uncover, increase heat, and cook 2 minutes or until liquid almost evaporates. Stir in 1 teaspoon of vinegar, and sprinkle with the parsley. Serve with lemon wedges.

balsamic vinegar, substitute a mixture of : (4 tsp)

1 tsp red wine vinegar and
2 tsp extra-virgin olive oil
1 tsp brown sugar