1. Put the vegetable oil in a large pot. cook the onion for about 3 minutes over medium heat.
2. add the potato and cook for about another 3 minutes.
3. then carefully add the water and simmer covered for another 15 minutes.
4. now add the peas and simmer for another 3 minutes. allow to cool before blending the soup in batches.
5. you'll now pass the soup through a sieve if you want it to be a silken texture, so put the sieve over the pot and strain the soup.
6. add salt and pepper to taste, reheat and serve.
7. if you like the texture of the soup the way it is after the blending, just reheat, salt and pepper to taste and serve.
8. you can finish this soup with a dollop of sour cream, bacon pieces or both.