In large saute pan over medium heat add 2 tablespoons oil, onions, chiles and saute for 3 minutes until translucent. Add chicken thighs and lightly brown. Add 1/4 cup garlic and saute. Deglaze with beer and chicken stock. Cook for 3 to 5 minutes, until chicken is 3/4 of the way cooked. Remove chicken from saute pan, and let cool, reserve pan and braising broth.
In medium saute pan heat another 2 tablespoons olive oil and lightly caramelize remaining 1/2 cup garlic. When done, remove from heat, and let cool.
In medium mixing bowl, combine, flour, salt and pepper, oregano, paprika, and chili powder. Combine thoroughly, add cooked garlic and mix into a paste.
Take cooled, cooked chicken and press paste on to the chicken. Heat remaining 2 tablespoons of olive oil in garlic pan, and gently place chicken in the pan. Lightly brown chicken on both sides.
Simmer reserved braising broth and add red wine vinegar. When chicken is cooked on both sides, pour vinegar broth over chicken and let simmer for 3 to 5 minutes.
Garnish with green onions.