Preheat the oven to 350 degrees F. Pour the cornflakes on a rimmed baking sheet and sprinkle the seasonings and oil over the top. Toss by hand and spread evenly over the baking sheet. Bake for 10 minutes, then cool.
For the Cilantro Dressing:
Place all the ingredients in the blender. Puree until smooth and emulsified. Then pulse in 1-2 tablespoons of water if needed to reach your desired consistency. Salt to taste.
For the Green Mango Chaat:
Peel and dice the mangoes. Place in a large salad bowl, with the onions, cilantro, peanuts, and raisins. Toss with the cilantro dressing and refrigerate until ready to serve. Toss in the corn poha right before serving, so they stay crisp.