For pickled onions: In a resealable plastic bag, combine vinegar, sugar, red onion and jalapeno pepper. Seal bag; turn to coat. Let sit 10 minutes or so to allow sugar to dissolve, then place in refrigerator to marinate for 24 to 48 hours. Drain and discard marinade before serving. For chicken: In a small skillet, toast oregano, cumin, fennel, ancho chile, caraway, coriander and cinnamon over medium-high heat until fragrant, 1 to 2 minutes. Let cool.