In a medium bowl, add the sliced chicken, half of the corn starch and 1 tsp soy sauce. Toss to combine and let stand for 5 minutes.
Meanwhile, in a separate bowl, stir together the chicken broth, remaining corn starch and soy sauce, and the vinegar until smooth.
Heat half the vegetable oil in a large skillet over high-heat. Add the chicken and cook, turning once, until golden; about 2-3 minutes per side. Transfer to clean plate.
Using the same skillet, add the remaining vegetable oil, garlic, and ginger and cook, stirring frequently for about 1 minute.
Add the snow peas, broccoli, and half of the green onions. Cook, stirring occasionally, until the vegetable begin to soften; about 2 minutes.
Pour the chicken broth mixture into the skillet and add the chicken back. Stir to coat everything and allow to cook for additional 4-6 minutes until sauce thickens.
Remove from heat and allow to cool for 1-2minutes before serving.
Serve over a bed of rice, topped with the remaining green onions, and sprinkled with sesame seeds, if desired.