Add sauce ingredients to slow cooker. Whisk until combined then set aside.
In a large skillet, heat sesame oil over medium heat. Add turkey, garlic, and onion.
Cook until browned (about 10 minutes), stir to prevent burning.
Add turkey to slow cooker and stir until sauce is evenly distributed.
Add bell peppers and edamame. Stir.
Cook on high for 2 hours or low for 4 hours.
Mix cornstarch and water in a small bowl or cup, add to slow cooker. Cook on high for 30-60 minutes, until sauce is thickened. Stir often.
Serve over rice or noodles.