Add 4cm of cold water or half a cup of cold water to a large pt. Add the onion and garlic and cook over a medium heat for 5-7 minutes until the onions are transparent.
Add all of the frozen peas and the stock and bring up to a boil then turn down and simmer for 10-15 minutes until the peas are cooked.
Remove from the heat and let it cool slightly before blending in either a blender or I use a stick blender and blend it in the pot until it's lovely and smooth.
Ladle into warm soup bowls and garnish with some of the left over mint leaves.