In a medium bowl, whisk together the cornstarch, salt, and pepper. In a separate shallow dish, beat the eggs.

Dip each piece of chicken in the beaten eggs, letting any excess drip off. Then, dredge the chicken in the cornstarch mixture, making sure it's fully coated.

Heat about ½ inch of vegetable oil in a large skillet or pot over medium-high heat. You'll know it's ready when a small sprinkle of cornstarch sizzles immediately.

Carefully place the coated chicken pieces in the hot oil, making sure not to overcrowd the pan. Cook for about 3-4 minutes per side, until golden brown and cooked through. The chicken should be crispy on the outside and no longer pink inside.

Remove the cooked chicken and place it on a plate lined with paper towels to drain any excess oil.

In a separate saucepan, whisk together the pineapple juice, rice vinegar, brown sugar, ketchup, soy sauce, cornstarch, and grated ginger.

Bring the sauce to a simmer over medium heat, stirring constantly. Cook until the sauce thickens, about 2-3 minutes. It should coat the back of a spoon.

Add the cooked chicken to the saucepan with the sweet and sour sauce. Toss gently to coat all the chicken pieces evenly.

Serve immediately over cooked rice or noodles. Sprinkle with the sliced green onions for a fresh, flavorful garnish.