Rinse the dried pinto beans thoroughly under cool running water.
Sort through the beans and remove any debris, damaged beans, or small stones.
Place the rinsed beans in a large pot and cover them with water.
Allow the beans to soak for 8 hours or overnight.
After soaking, drain the beans in a colander.
Return the drained beans to the pot.
Add 1 quart of water to the pot.
Place the pot over medium-high heat and bring the water to a rapid boil.
Once boiling, reduce the heat to a gentle simmer.
Cover the pot with a lid.
Simmer the beans for 1 1/2 hours, or until they are fork tender.
Add the tomato paste, diced onion, minced garlic, chili powder, ground cumin, paprika, salt, brown sugar, black pepper, and cayenne pepper, if using.
Stir until the tomato paste and seasonings are evenly incorporated.
Bring the mixture back to a boil.
Reduce the heat to a gentle simmer.
Cover the pot with a lid.
Simmer for an additional 1 1/2 hours, stirring occasionally, until the beans are tender and the sauce has thickened.
Taste and adjust the seasoning, if necessary.
Serve warm with hot sauce, grated cheese, sliced jalapeño, sour cream, green onion, parsley, or cilantro, if desired.