Drain the beans through a strainer set over a bowl. Place the beans in a large soup pot or Dutch oven. Measure the soaking water in the bowl, and add enough water to it to measure 2 1/2 quarts. Add this to the pot with the beans, turn the heat to medium-high and bring to a gentle boil. Skim off any foam and/or bean skins.

Meanwhile, heat 1 tablespoon of the oil over medium heat in a large, heavy skillet and add the onions, carrots, and peppers. Cook, stirring often, until the vegetables are tender and fragrant, about 8 to 10 minutes. Add 2 of the garlic cloves and continue to cook for another minute or so, until the garlic is fragrant. Season to taste with salt, add another tablespoon of oil and add the paprika. Cook, stirring, for a couple of minutes, until the vegetables are well coated with paprika and the mixture is aromatic. Add a ladleful of simmering water from the beans to the pan, stir with a wooden spoon or heatproof spatula, scraping the bottom and sides of the pan to deglaze, then stir this mixture into the beans. Add the tomato paste and bay leaf, reduce the heat, cover and simmer 1 hour.

Add the oregano, the remaining garlic cloves, salt to taste, cayenne, vinegar, and sugar, and continue to simmer for another hour. The beans should be thoroughly tender and the broth thick and fragrant. Taste and adjust salt, and add more cayenne if desired. For a thicker stew, strain out 1 heaped cup of beans with a little liquid and purée. Stir back into the stew.

Just before serving, stir in the parsley. Serve over noodles or thick slices of country bread, topping each portion with a large dollop of drained yogurt.