Cut the boneless, skinless chicken breasts or tenders into bite-sized, approximately 1-inch pieces. Pour the cornstarch into a shallow dish. Add the chicken pieces to the dish and toss thoroughly to ensure all the chicken is evenly coated with cornstarch. This coating will help the chicken get a light crust when browned.

Heat the olive oil in a large skillet over medium-high heat. Once the oil is shimmering, add the cornstarch-coated chicken pieces. Allow the chicken to brown lightly on each side, turning as needed. Do not cook the chicken all the way through—just develop a golden exterior. Once browned, transfer all the chicken pieces to the basin of a 6-quart slow cooker.

In a medium bowl, whisk together the orange marmalade, reduced-sodium soy sauce, white vinegar, sesame oil, ground ginger, minced garlic, crushed red pepper flakes, and 1 teaspoon of sesame seeds. Ensure all ingredients are well incorporated, forming a smooth sauce. I like to taste the sauce here and add a little extra ginger if I want more zing.

Pour the prepared orange sauce from Step 3 over the browned chicken in the slow cooker. Stir gently to make sure all the chicken pieces are well coated. Cover the slow cooker and cook on LOW for 2 to 3 hours. Stir halfway through the cooking time to ensure the sauce doesn't stick or burn and the chicken cooks evenly.

Once the chicken is cooked through and the sauce is thickened, garnish the dish with additional sesame seeds and chopped scallions before serving. This final touch adds both flavor and a nice pop of color. I like to serve this dish over steamed rice for a perfect meal.