For the Ragout of Peas and Romaine Lettuce
Bring a large pot of salted water to a boil and set a bowl of ice water on the side.
Boil the peas for about 20 seconds, until tender, and chill in the ice water. Peel the skins from 3 cups of the peas and set aside. Pour the cream into a medium saucepan and bring to a simmer. Transfer to a blender with the remaining peas and puree until smooth; pass through a fine-meshed sieve into a bowl set over ice. Stir until chilled.
When ready to serve, heat the olive oil in a medium sauté pan over medium heat and add the onions. Cook, stirring, until soft but not colored, about 2 minutes. Add the reserved peeled peas and romaine lettuce and stir until heated through. Stir in half of the pea puree and the oregano; season with salt and pepper and keep warm.