Soak pinto beans in water for at least 8 hours to soften. Drain and rinse beans. In a large stockpot, sauté bacon over medium heat, rendering fat into pan, about 5 minutes. Add onion and jalapeño and sweat for 5 minutes. Add reserved beans and enough stock to cover beans. Bring mixture to a boil then reduce heat to medium-low. Add tomatoes, beer, and salt. Simmer over medium-low heat for 1½ to 2 hours until beans are tender, stirring and tasting occasionally to check for doneness. Garnish with chopped cilantro and serve.