Heat oil in a medium-sized pot.
Cut the chicken into one-inch pieces and place them in a bowl.
Whisk the eggs and pour them over the chicken. Coat the chicken with the egg mixture.
In a bowl add the flour, cornstarch and salt.
Dip the battered chicken into the flour mixture and fully coat the chicken.
Fry the chicken until golden brown. You may need to cook the chicken in two to three batches.
Remove the chicken from the oil and transfer to a paper towel covered dish.
To prepare sauce:
In a bowl, add ketchup, vinegar, sugar, soy sauce and minced garlic. Whisk the ingredients together until combined.
In a skillet, heat about 1/4 c of oil.
Add vegetables to the oil and cook until they begin to soften.
Add the pineapples to the pan and stir into ingredients.
Pour the sauce into the skillet and bring it to a simmer.
Add the chicken to the skillet and mix into the sauce.
Simmer for a few minutes and then remove from the heat.
Allow the chicken to rest for about 10 minutes prior to serving.