Rinse them and place them in a pot. Put enough water to cover them. Bring them to a boil, then change the water and cover the beans again with water and boil for about an 45 minutes to an hour.
Sauté the chopped onion in olive oil until translucent. Add the garlic and continue to sauté for about a minute. Add the beans and mix gently until they are covered with the olive oil.
Add the tomatoes and about 1/2 cup hot water. Add pepper and salt to taste. Bring to boil and lower heat and simmer for about 25 minutes, until beans are soft and liquids are absorbed. Check and add water as needed.
Remove from heat and let it cool. Serve with feta and bread or rusk.