The great thing about this soup is that you can make it all year round because you use frozen peas. I do think that peas are the only vegetables that taste better frozen than fresh.
Bring the stock to the boil in a pan and add the peas. Cook for 1 minute, then add the crème fraîche. Remove from the heat and whizz in the blender with the mint leaves until smooth. Pour through a sieve to remove any lumps.
Reheat gently, season to taste and serve in warmed bowls.