In a midsize pan sauté the peppers and onion over low heat until soft, around 10 mins.
If using fresh tomatoes, peel them by creating an X mark with a knife at their bottoms and placing them in a bowl with hot water for a few minutes. Take them out and their peel should be easy to remove from the X mark.
Cut the peeled tomatoes into small pieces and add them (or the canned tomatoes) to the pan. Bring to a boil and lower the heat to a simmer.
Add the tomato concentrate and the spices to the pan and let cook until the tomatoes lose all shape and become almost like a paste, around 30-45 minutes. If using canned tomatoes 20 minutes of cooking should be enough.
While the sauce is cooking make sure the water doesn't run out and the sauce isn't burning in the bottom, mix occasionally.
Add the feta cheese, if using, at the end of the cooking.
Break each egg separately into the pan in different areas. You can break them before in cups so it is easier to add them to the pan.
Cover the pan - preferably with a transparent lid and let cook over low to medium heat.
When the white becomes opaque, the dish is ready - around 5-10 minutes. If you prefer the yolk to be fully cooked, let it cook for a few more minutes over low heat.