Set a medium sized pan to medium high heat on the stove.
Add half the olive oil and veggies. Sauté vegetables, stirring regularly every couple of minutes for 10 minutes. If / when they start browning and if you smell them almost starting to burn, add water, the rest of the olive oil, and reduce heat to medium. Add salt and pepper if desired at this time. Cook, uncovered, stirring regularly, until liquid has cooked out (which will take 5-10 minutes).
Transfer to a bowl and garnish with diced green onion and serve.