Make the Sauce:

1. In a medium sized pot measure soy sauce, vinegar, brown sugar, ground ginger, onion powder and 3 teaspoons cornstarch. Using a whisk, mix ingredients together and bring to a boil over medium high heat.
2. Whisk occasionally.
3. After it starts to boil, cook the sauce until it looks like it's just beginning to thicken, this will take around 5-7 minutes.
4. Then turn the heat down to low and let it continue to cook and all the while, keep whisking occasionally.
5. Let it simmer for about 10 more minutes.
6. Before leaving it to simmer on low, make sure the sauce is nice and thick - enough to coat the chicken.
7. If the sauce needs to be thicker, mix 1 teaspoon cornstarch in 1 tablespoon. cold water, or just enough to dissolve the cornstarch, then pour into the sauce. Stir and bring back to a boil again.
8. This is a good time to add spices, vinegar or sugar if you want to adjust the flavor so carefully taste the sauce.
9. After simmering on low for 10 minutes after the last addition, remove from heat and let the sauce cool.
10. Set it aside until the chicken and pineapple skewers are cooked.

For the Chicken and Pineapple Skewers:

1. Cut the chicken and pineapple into cubes approximately the same size.
2. Begin to load the chicken and pineapple onto the skewers
3. Sprinkle lightly with salt.
4. Preheat a stovetop pan (I like to use my cast iron grill pan) on medium high heat and preheat your oven to 400°F.
5. Prepare a baking sheet by lining with foil or a silicone baking liner. This makes cleanup easier.
6. Drizzle a little oil on the bottom of the stovetop pan.
7. Lay the skewers down and cook to brown all sides of the chicken. The center will likely still be raw.
8. Lay browned skewers on the baking sheet in a single layer.
9. Bake until chicken is cooked through, usually takes about 10-15 minutes.
10. Brush with prepared sauce.
11. Garnish with chopped green onions or sesame seeds.