Heat olive oil in a large skillet over medium heat.
Add diced onion and minced garlic to hot skillet. Cook until onion becomes translucent (approximately 2-3 minutes).
Cut chicken into small thin strips about 3/4 inch wide.
Add the chicken to your skillet. Crank the heat up to medium high and let the chicken get a little color all all sides. Stir frequently to prevent sticking. Chicken does not need to cook through at this point. Once it no longer looks raw on the outside you're ready to move forward.
Add all remaining ingredients to pan. Gently stir.
Lower heat to medium-low. Cover. Simmer for 25-30 minutes. Sauce will thicken as it simmers.
Serve over cauliflower rice, vegetables, or traditional rice. Top with chopped green onion.
Do not use any coconut milk other than canned unsweetened full fat coconut milk. I get this question a lot. Canned coconut milk is thick and not as watered down as the kind you'll find in the refrigerated section of the store. I prefer Thai Kitchen (make sure it says unsweetened and does not say low fat) but there are other brands that work well too!