Using a medium-sized saucepan, combine the semi-cooked chickpeas, chopped onion, salt, pepper, oregano, bay leaves, and olive oil.
Add 4 cups of water and place the pan over medium-high heat.
Bring to a boil, adjust the heat to medium-low and continue simmering until the chickpeas are fully cooked -- generally takes 40 to 45 minutes.
Using a small bowl, combine flour and lemon juice, and mix until the flour has dissolved.
Add flour mixture into the soup and mix.
Taste and adjust seasoning, mix and cover with a lid.
After a couple of minutes, take the pan off the heat.
Transfer gaarbanzo bean soup into serving bowls.