Rinse 3 cups of dried beans thoroughly in cold water. Place them in a large bowl with 2 liters of cold water and 1 tablespoon of salt. Cover and let soak overnight at room temperature.

Drain the soaked beans and transfer to a large pot. Add enough fresh water to cover the beans by 2 inches. Bring to a boil over high heat, skimming off any foam that rises to the surface.

Once boiling, reduce heat to medium and cook for 30-40 minutes until beans are tender but not falling apart. Drain the beans and set aside.

While beans are cooking, chop 1 onion, 2 green peppers, and 1 red pepper into medium-sized pieces.

In a clay pot or heavy-bottomed pot, heat ½ cup vegetable oil over medium heat. Add the chopped onion and sauté until softened and translucent, about 5 minutes.

Add the chopped peppers to the pot and cook for 3-4 minutes. Stir in 1 tablespoon of tomato paste and cook for another minute.

Add the drained beans to the pot. Squeeze half a lemon over the beans to prevent them from splitting. Season with cumin, black pepper, red pepper flakes, turmeric, and salt to taste. Add 1 sugar cube to balance the acidity.

Pour in 6 cups of water, ensuring the beans are well covered. Cover the pot with aluminum foil, then place the lid on top for better heat retention.

Bring to a gentle boil, then reduce heat to low. Simmer for 20 minutes after it reaches a boil. The beans should be creamy and tender with a thick, flavorful sauce.

Test a bean by pressing it between your fingers. It should be soft and creamy inside while maintaining its shape.