In a saucepan, set to medium heat, combine 1 cup of water, brown sugar, soy sauce, honey, garlic and ground ginger.
In a small bowl, combine the cornstarch with the 1/4 cup cold water and whisk until dissolved. Add the cornstarch mixture to the saucepan.
Heat the sauce until it thickens. It should be thick enough to coat the back of a spoon.
Place frozen meatballs into slow cooker.
Pour over teriyaki sauce and crushed pineapple.
Heat on high for 2 to 3 hours or on low for 4 to 5 hours.
To serve, sprinkle with sesame seeds and chopped scallion.