Place first 6 ingredients in a food processor; process 1 minute or until a thick paste forms.
Heat a large Dutch oven over medium-high heat. Coat pan with cooking spray. Add pork to pan; cook 4 minutes, browning on all sides. Remove pork from pan.
Add chile mixture to pan; cook 2 minutes or until fragrant, stirring occasionally. Stir in beer, scraping pan to loosen browned bits. Add pork and cinnamon; bring to a simmer. Cover, reduce heat, and simmer 2 hours or until pork is tender.
Remove pork from pan; shred into large pieces with 2 forks. Stir shredded pork and sweet potato into pan; cover and simmer for 20 minutes or until potato is tender. Discard cinnamon stick. Garnish with cilantro, if desired.