Place the ham (or bacon) fat in a saute pan and render fat. Remove any undesirable remaining fat solids, leaving rendered fat in the pan.
Add oil to the pan and add chopped onion. Saute until lightly browned.
Add thyme and tomato paste to the pan with the onions. Stir and simmer for about 5 minutes.
Add drained pigeon peas to the tomato mixture, add water and season with salt and pepper. Bring to a boil and add the rice. Lower the heat, cover and simmer for 20 - 30 minutes until the rice is tender.