For the plantain soup, peel and dice the plantains, onions and apple. Peel and chop the garlic.
Heat oil in a pot and sauté onions with garlic. Add plantains and apple and sauté briefly, tossing constantly.
Season with salt, curry, pepper and lemon juice and add vegetable soup. Bring soup to a boil and continue to simmer for 5 minutes.
Remove from heat and blend the plantain soup well.