In a large heavy pot over medium heat, add 2 tablespoons of olive oil and the onion and sauté for about 5 minutes. Add the bell pepper and continue to cook another 3 to 4 minutes. Add a drop of olive oil and add the garlic, chili powder, paprika, cumin, oregano and cayenne and stir for another minute, until fragrant. Add the beef and a pinch of salt and continue cooking, breaking the meat into pieces as it browns. Add the chopped tomatoes, tomato paste, beans and beer and bring the chili to a boil. Reduce the heat to low and simmer for 20- 30 minutes. Finish with a splash of sherry vinegar, and adjust the seasoning. Serve with sliced avocado.