How to Make It
Stir together yogurt, lemon zest and juice, sugar, and salt in a small bowl. Store in an airtight container in refrigerator until ready to use, up to 3 days.
Bring a large pot of salted water to a boil over high. Fill a large bowl with ice water. Add English peas to boiling water; cook 4 minutes. Add snap peas; cook 2 minutes. Add snow peas; cook until all peas are crisp-tender, about 30 seconds. Using a spider, remove pea mixture from boiling water, and plunge into ice water; let cool 3 minutes. Drain well; transfer to a medium bowl.
Heat oil in a small skillet over medium-high. Add cumin seeds and mustard seeds; toast, stirring constantly, until very fragrant, 40 seconds to 1 minute. Stir in ginger, chaat masala, and chile to form a thick paste. Remove from heat; add to pea mixture in bowl, and toss to combine. Season to taste with salt and pepper. Refrigerate, uncovered, until chilled, about 10 minutes.
Transfer spring pea chaat to a serving platter; drizzle with spicy mango-mint chutney and 1/4 cup lemon raita. Garnish with cilantro leaves and pea shoots.