Preparation Toss first 3 ingredients in large glass bowl. Add juice and vinegar; press down to submerge onions. Cut 1/2-inch-long slit in narrow tip of chile and add to onion mixture. Top mixture with small plate to weigh down slightly. Cover; refrigerate overnight. Drain. DO AHEAD Can be made 1 week ahead. Keep refrigerated.
Preparation Toss first 3 ingredients in large glass bowl. Add juice and vinegar; press down to submerge onions. Cut 1/2-inch-long slit in narrow tip of chile and add to onion mixture. Top mixture with small plate to weigh down slightly. Cover; refrigerate overnight. Drain. DO AHEAD Can be made 1 week ahead. Keep refrigerated.