Grate zest and squeeze juice from lemons. Mix zest and lemon juice, olive oil, garlic, salt, and red pepper flakes in a one-gallon, self-sealing plastic bag. Add chicken breasts and refrigerate for at least 30 minutes, but no more than 2 hours. Brush grill grates with oil or non-stick spray. Place chicken on grill and cook until firm, approximately six minutes per side. Heat beans and vinegar in saucepan over medium heat for five minutes stirring often. Stir in cilantro. Spoon bean mixture on dinner plates. Cut chicken on diagonal in 1/2-inch thick slices and fan over bean ragout. Garnish with cilantro. Serves 6 to 8.