In a dry skillet, lightly toast the ogbono seeds over medium heat for about 2-3 minutes until fragrant. Be careful not to burn them.
Allow the toasted ogbono seeds to cool, then grind them into a fine powder using a blender or food processor. In a large pot, heat the palm oil over medium heat.
Add the chopped onions and sauté until translucent.
Stir in the minced garlic and cook for another minute.
Add the chopped red and green bell peppers to the pot and sauté until they soften.
Add the chopped tomatoes and cook for about 5 minutes until they break down and release their juices.
Stir in the ground ogbono powder, and then gradually add the vegetable broth or water, stirring continuously to combine the ingredients and achieve a smooth consistency.
Add the ground crayfish (if using), dried bitter leaf or scent leaf (if using), salt, and freshly ground black pepper. Mix well.
Cover the pot and let the soup simmer for about 10-15 minutes, allowing the flavors to meld together and the ogbono to thicken the soup.
Taste the Ogbono Soup and adjust the seasoning if needed.
Remove from heat and let the Ogbono Soup sit for a few minutes before serving.
Serve the Nigerian Ogbono Soup hot with fufu, pounded yam, or any preferred accompaniment.