Sweet and Sour sauce. In a small saucepan add oil over medium heat and saute garlic and ginger for about 1 minute. Stir in sugar, vinegar, honey, ketchup, soy sauce. Simmer until sugar dissolves.
Meanwhile, in a small bowl whisk together cornstarch and water and pour the mixture into the saucepan. Simmer on low heat for 10 minutes until the sweet and sour sauce starts thickening. Set aside.
Chicken prep. In a medium bowl add chicken, season with salt and pepper, and stir in the cornstarch. Make sure all the chicken pieces are covered in cornstarch. Set aside.
Stir fry. In a large skillet or wok over medium to high heat add 2-3 tablespoon of vegetable oil and cook the chicken until golden brown on all sides (about 3-4 minutes.) Remove from pan and set aside in a plate lined with a paper towel.
In the same skillet add vegetables, cook for few minutes until they get almost tender and throw in the pineapple. Stir well and return the chicken to the pan, pour the sauce on top. Stir and simmer for 1-2 minutes. Taste the sauce for seasoning, add salt and pepper if needed.
Serve with scallions, sesame seeds, and rice, noodles, or another favorite side.