Balsamic Chicken & Broccoli

1 tbsp. olive oil
2 cloves garlic, minced
1/2 sm. onion, thinly sliced and cut into thirds
2 tbsp. diced shallots
1/4 c. white wine
2 chicken breasts, cut into strips
3 tbsp. balsamic vinegar
2 c. broccoli spears
1 c. mushrooms, thickly sliced
1/3 c. chicken stock
1/4 tsp. salt
Black pepper

Heat oil in a heavy pot. Add garlic, onion, and shallots, and cook until light golden. Keep pot covered between stirrings and use a tbsp. or so of the wine if more liquid is needed. Add chicken and enough of the wine to kepp meat from sticking to the pot. Cook until chicken is white all the way through, about 5 to 7 minutes (use more wine, if needed). Remove chicken and sauteed vegetables with slotted spoon. Add vinegar to pot, increase heat, and stir with a wooden spoon, scraping bits from the bottom, until liquid is reduced to about half its original volume. Reduce heat. Return chicken and sauteed vegetables to pot; add broccoli, mushrooms, chicken stock, remaining wine, and salt. Cook at a gentle simmer until broccoli turns bright green. Serve over pasta and dust with pepper.