Drain beans, reserving liquid; set aside. Heat oil in a medium heavy-bottomed saucepot over medium-high heat. Add beef, onions and garlic; cook until browned, breaking up meat with a wooden spoon, about 10 minutes. Stir in reserved bean liquid, diced tomatoes, tomato sauce, chili powder and cumin. Bring beef mixture to a boil. Reduce heat to low and simmer, stirring occasionally, until sauce thickens, about 1 hour.
Stir reserved beans into meat mixture. Cook until heated through, about 10 minutes more. Stir in sugar; season with adobo. Divide chili evenly among serving bowls. Garnish with salsita, if desired.