Step 1: Prepare the chicken by cutting boneless, skinless chicken breasts into uniform 1-inch bite-sized pieces. Pat them dry with paper towels.
Step 2: Set up your dredging stations. In a shallow bowl, combine all-purpose flour, cornstarch, baking powder, garlic powder, Himalayan sea salt, and black pepper. Whisk well. In a second shallow bowl, whisk together the eggs and milk.
Step 3: Dredge the chicken pieces. First, coat each piece thoroughly in the flour mixture, shaking off any excess. Then dip it into the egg wash, allowing excess to drip off. Finally, return it to the flour mixture for a second coating, pressing gently to ensure full coverage.
Step 4: Heat the frying oil. Pour vegetable oil into a large heavy-bottomed skillet or Dutch oven to a depth of about 2 inches. Heat over medium-high heat until a thermometer reads 375°F (190°C).
Step 5: Fry the chicken. Carefully add chicken pieces to the hot oil in batches, ensuring not to overcrowd the pan. Fry for 4-6 minutes, or until golden brown, crispy, and cooked through (internal temperature of 165°F/74°C).
Step 6: Drain the chicken. Using a slotted spoon, remove the cooked chicken bites from the oil and transfer them to a wire rack set over a baking sheet to drain any excess oil.
Step 7: Toss with sauce. In a large bowl, pour the sweet chili sauce over the warm, crispy chicken bites. Toss gently until all pieces are evenly coated.
Step 8: Garnish and serve. Transfer the sauced chicken to a serving platter and garnish generously with sesame seeds and chopped green onions. Serve immediately.