Sauté onions, garlic mixed with salt, and tarragon in olive oil until onions are soft.
Add peas and 1/4 cup of cream, stirring until peas are heated through.
Purée pea and cream mixture in batches in the blender with the chicken broth. Leave some of the peas whole. Return mixture to pot.
Add lemon juice and more cream to desired taste and consistency. Season with black pepper.
Ladle the soup into bowls and place 3 to 6 mint leaves in each bowl. It’s important to put the mint in while the soup is still warm but removed from the heat for the best flavor infusion.