Prepare a medium pot of boiling salted water, and keep a large bowl of ice-cold water nearby. Blanch the broad beans for 2 minutes, then add the peas and continue cooking for an additional 2 minutes. Drain the beans and peas, and immediately transfer them to the ice-cold water. Let them cool for a couple of minutes before draining them again.
Peel the broad beans by gently squeezing each one between your thumb and index finger, allowing the beans to pop out of their skins. Discard the skins.
In a large bowl, crumble the feta cheese and add the lemon zest, lemon juice, and chopped mint (reserve some for garnish, if desired). Gradually drizzle in the olive oil while mashing the mixture with a fork until it reaches a softened, moist, and creamy consistency.
Add the cooled beans and peas to the feta mixture (reserving some for garnish, if you like) and stir lightly with a fork until everything is well combined.
Assemble the toast by dividing the mixture among the 4 slices of toasted bread, spreading it evenly. Garnish with the reserved zest, mint, and peas, and drizzle with extra olive oil. Serve immediately.