Melt the olive oil and butter in a medium saucepan or skillet over medium heat. Add the sliced green onions and cook for a couple of minutes. Slice the butter lettuce, but don’t shred. (You can even use bagged lettuce.)

Layer half of the lettuce into the saucepan over the onions. Sprinkle the peas on top. Then add the remaining lettuce. Season with a pinch of salt and pepper.

Cook for a minute or two, and then sprinkle the flour over the vegetables. Stir until the vegetables are coated. Slowly pour in the stock, cover, and increase the heat to achieve a simmer. Cook for 4 or 5 minutes, or until the peas are tender.

Taste and season with salt and pepper as needed. Add finely chopped mint leaves if desired and stir. Pour off the cooking liquid, add the lemon juice, and serve.