If using frozen edamame, cook according to package instructions until tender. Drain and let cool.

In a medium bowl, mash the avocado with a fork. Add the lemon juice, lemon zest, salt, and pepper. Mix until well combined.

In a small bowl, combine the olive oil, garlic powder, and red pepper flakes (if using). Brush this mixture onto one side of each slice of bread.

Toast the bread slices in a skillet over medium heat or in a toaster until golden brown.

Spread the avocado mixture generously on the toasted side of each slice of bread.

Top each open-faced sandwich with a portion of the cooked edamame.

Garnish with fresh parsley or cilantro before serving.