Add peas to a medium pot of generously salted boiling water. Cook until bright green and just tender, 3 to 4 minutes. Drain.
Heat oil in a large skillet over medium heat. Add onions and cook, stirring frequently, until just softened, about 3 minutes. Add pea shoots; cook, stirring occasionally, until just wilted, about 2 minutes. Season with salt and pepper. Stir in peas, then transfer mixture to a bowl. Let cool slightly.
Stir in yogurt, chopped mint, and zest. Season with salt and pepper and garnish with mint leaves; serve.
