Fry the onion and beef in a casserole dish until brown.
Peel the plantains and rub them with the lemon juice. Add to the casserole and fry for a further 5 minutes. Make sure you stir or the plantains may burn.
Add the remaining ingredients to the stew and then add some water making sure it covers all the ingredients.
Place a lid on the casserole and let it cook for about 2 hours on a low heat.
For the Ugali bring about 4 cups (1 litre) of water to boil
Now you slowly add in spoon by spoon the maize flour to the water. Keep on stirring until it slowly thickens. We added approximately 150g over 20 minutes while stirring constantly.
Ugali normally has a bit thicker consistency than mashed potatoes but it is up to you how you like it.
Serve with rice or a maize porridge.