Brown the beef and onion: Add the ground beef to a large stockpot and cook over medium heat, breaking it apart with a wooden spoon as it cooks. When the beef is nearly browned, add the diced onion and continue cooking until the beef is cooked through and the onion has softened.

Drain the beef and rinse the beans: Transfer the beef and onion mixture to a large strainer and drain well. Return the beef and onions to the pot. Add the pinto beans and both kidney beans to the same strainer, rinse thoroughly under cold water, and let them drain while you continue with the chili.

Bloom the garlic and spices: Set the pot over medium heat. Add the garlic and cook for about 30 seconds to 1 minute, just until fragrant. Add the ancho chile powder, chili powder, cumin, smoked paprika, oregano, onion powder, salt, black pepper and crushed red pepper flakes, if using. Stir constantly for about 1 minute to lightly toast the spices.

Add the tomato paste: Stir in the tomato paste and cook briefly, mixing it into the beef and spices until everything is evenly coated.

Build the chili: Add the drained beans, petite diced tomatoes, tomato sauce, beef broth, Worcestershire sauce, brown sugar and stir well.

Bring to a simmer: Increase the heat until the chili reaches a gentle boil, stirring frequently. Reduce the heat to low and simmer for about 30 minutes, stirring occasionally and scraping the bottom of the pot to loosen anything that may be sticking.

Adjust the thickness: Partially cover the pot with the lid slightly cracked to help contain splatters while allowing steam to escape. If you prefer a thicker chili, remove the lid during the second half of cooking and continue simmering uncovered until it reaches the consistency you like.

Taste and adjust: Stir the chili well, taste and add additional salt if needed before serving.