Soak the beans covered in water—either overnight or the quick soak method in which you place the beans in a pot, cover with water, bring to a boil, cover and remove from heat and let sit for 1 hour.
Drain the soaked beans.
In a cast-iron skillet heated up to medium high, cook the anchos on each side for a couple of minutes (or until they start to bubble and pop), turn off the heat and fill the skillet with warm water. Let them sit until soft and rehydrated, about half an hour.
In the pot you’ll be cooking your beans, heat up a teaspoon of canola oil and cook the onions for 5 minutes on medium. Add the garlic and cook for another minute. Throw the cooked onions and garlic in a blender and add the tomatoes, brown sugar, apple cider vinegar, paprika, cumin, oregano, water, hydrated ancho chiles, and salt. Puree until smooth. Set aside.
Add the pinto beans and beef broth to the pot. On high, bring the pot to a boil and then cover; turn the heat down to low and simmer for 1 hour, stirring occasionally.
At this time, stir in the reserved chile puree and then continue to cook the beans uncovered for another hour or until tender and the sauce has reduced. Taste and adjust seasonings. Serve warm.
If you can’t find dried ancho chiles, you can substitute either ancho chile powder or regular chili powder. I’d use 1/4 of a cup. These are not fiery beans, but if you want a bit more heat I’d throw in a bit of cayenne. And I always add a pinch of baking soda to my soaking beans to help with digestion issues. You may do the same.