In a cast iron pan over medium high heat, add the oil and once shimmering add the steak.
Cook, moving the steak around until seared, and then remove to a plate.
Add a drizzle more oil and add the garlic and cook for 20 seconds and then add all the vegetables.
In a bowl, whisk together the sauce while the veggies are cooking.
Add the steak back in to the pan along with the sauce and stir to coat. Allow to simmer at medium heat for 5 minutes or until the sauce has reduced a little and serve.
Notes
Stir fry can be kept in the refrigerator for 3-4 days.