Slice the plantain and put in a saucepan. Add the rest of the ingredients, bring to a boil and simmer for 20 minutes or until all of the ingredients are cooked. Puree with a hand blender until smooth. Taste and adjust the seasonings. Add food coloring if you wish. A little bit of red and yellow would result to a red orange color , the usual color of banana ketchup. Leave to cool then transfer to a wide mouth jar. Store in the refrigerator.