You can find sweet chili sauce in the Asian foods section of larger grocery stores or at an Asian grocer. Don't overmix the meatball batter after adding the breadcrumbs. An overmixed meatball will be dense rather than light and airy. I like a 1/2-ounce scoop for mini meatballs. If you use a larger scoop, the meatballs will take a bit longer to cook. If you can't find toasted sesame seeds and don't want to toast them yourself, substitute black sesame seeds.