In a large bowl, combine the chicken pieces, lemon juice, ginger-garlic paste, salt, red pepper flakes, chili powder, Kashmiri chili powder, turmeric, cumin, and garam masala. Mix until the chicken is thoroughly coated.
Cover the bowl and let the chicken marinate in the refrigerator for at least 60 minutes, or up to 2 hours.
When you are ready to cook, add the beaten egg, gram flour, rice flour, and cornstarch to the marinated chicken. Stir well until a thick batter forms and clings to each piece.
Pour the oil into a heavy-bottomed pot or Dutch oven and heat over medium-high heat until it reaches 350°F (175°C) on a thermometer.
Working in small batches, carefully place the battered chicken pieces into the hot oil one by one. Do not overcrowd the pot.
Fry for 3 to 5 minutes, turning occasionally, until the pakodas are a deep golden brown and cooked through.
Check for doneness by ensuring the internal temperature of a piece reaches 165°F (74°C).
Use a slotted spoon to remove the chicken pakoda from the oil and place them on a wire rack to drain excess oil.
Allow the oil to return to 350°F (175°C) before frying the next batch. Serve immediately.