Add peas, mint, Parmesan, lemon juice, olive oil, and salt to a blender or a mini food processor. Process until it comes together and is the consistency of guacamole.
Meanwhile, toast the sourdough. Divide smashed peas among the four toasts, then dollop with a spoonful or two of ricotta. Drizzle with olive oil and season with a few grinds of black pepper.
