For the Yucatan Red Recado, place all ingredients in blender container; cover. Blend on medium speed until smooth.
For the Mexican Slow-Roasted Pork, mix juices, garlic and Yucatan Red Recado in medium bowl until well blended. Pour over pork butt in large resealable plastic bag. Rub marinade all over pork. Cover. Refrigerate overnight.
For the Pickled Red Onions, place onions in medium heatproof bowl. Add boiling water to cover. Let stand 15 minutes. Drain and rinse with cold water. Meanwhile, bring remaining ingredients to simmer in small saucepan on medium-high heat. Remove from heat. Let stand 15 minutes. Pour over onions in medium bowl. Cover. Refrigerate at least 2 to 3 hours to marinate onions. Drain before serving.
Preheat oven to 325°F. Remove pork from refrigerator. Place in large baking dish. Let stand 15 minutes.
Bake 4 hours or until pork is very tender. Shred pork using 2 forks. Mix with sauce in baking dish. Serve with pickled red onions.