This is a meal typically made by the Manyu people of Cameroon.
If you are using dried eru/okazi, soak it in warm water for at least 30 minutes before cooking. I usually add a little baking soda (1/2-11 teaspoon) into the water before soaking so it helps brighten the colour of the eru and softens it. But that is completely optional so you could leave it out.
Put meat and stock into a large pot. Bring to simmer on medium high heat and let it simmer for about 5-7 minutes until the stock is almost completely dried.
Add in spinach and let it cook for 5 minutes. It will wilt greatly and release its juices. Stir the spinach and let it cook again for another 5 minutes or less. Do not let the spinach become brown.
Now rinse the eru thoroughly and add into the spinach. Mix until both vegetables are well incorporated. Pour in the oil and stir well. Let them simmer together for another 5 minutes while you stir from time to time.
Add in the seasoning cubes (Maggi), pepper (if using), crayfish and fish. Give that a good mix. Let it cook together for about 5 more minutes. At this point, taste the seasoning to ensure it is perfect. Your eru should be moist but not watery. If it is too dry, add some water or oil to make it moist. If it is too soft, let it cook some more so the water dries up.
Turn off the heat and serve warm with fufu or garri of choice.