Bring a large saucepan of salted water to a boil. Add the peas and cook for 1 minute. Drain and immediately rinse under cold water until room temperature. Drain well, then transfer to a food processor. Pulse until almost smooth.
Add the avocado, lime zest and juice, and cilantro. Pulse until almost smooth. Add the scallion and jalapeno and pulse until well incorporated. Season to taste with salt.
Transfer to a serving bowl and garnish with cilantro. Serve with the cucumber slices.