Braised Mustard Greens

Ingredients

• 2 t olive oil
• 1 medium onion, cut into 1/4-inch dice
• 2 small shallots, minced
• 3 clv garlic, peeled &; minced
• 1⁄2 c chicken stock
• 2 lb mustard greens, washed left whole with thick stems trimmed
• 1⁄4 t crushed red-pepper flakes, or to taste
• salt and pepper, to taste
• 1 t red wine vinegar
• 1⁄4 t whole mustard seeds, or to taste