Rinse chicken under cool water then pat dry using paper towels. Cut chicken into 1" cubes then toss with 1 Tbsp cornstarch to coat. Place large skillet over medium-high heat then add oil. When the oil is hot, add chicken, separating pieces that are stuck together. Cook chicken until nicely browned, but not necessarily cooked through (about 6–7 minutes), stirring occasionally.
Meanwhile, stir together orange juice, marmalade, honey, soy sauce, lemon juice, ginger, garlic, red pepper, sesame seeds and sesame oil in a medium-sized mixing bowl.
Once chicken is nicely browned, pour sauce into skillet then bring to a bubble. Reduce heat to medium-low and simmer for 15 minutes.
Stir together ¼ cup water with 2 Tbsp cornstarch. After 15 minutes, the sauce will have thickened slightly due to evaporation as well as from the cornstarch that was added to the chicken. If you would like the sauce to be thicker, stir the cornstarch slurry into simmering sauce, a little at a time, until you have achieved the desired consistency.
Remove from heat then serve over a bed of fresh steamed rice. Garnish with sliced green onion and a few extra sesame seeds on top. Enjoy!
It is so much easier to cut chicken breasts when they are slightly frozen. Just pop them into the freezer for 10–15 min before slicing and it will be much easier to cut into cubes!