Thai Peanut Stir Fry to die for!

This recipe was inspired by the bottled Thai Peanut Stir Fry sauce you can buy in the grocery store. After being alarmed at how much it cost, I read the ingredient list, went home and created my own version. After a couple trials I have what I feel is a far superior sauce. Every time I make this my husband tells me I need to bottle it, sell it, and make our millions. Instead, alas, I am sharing it with you. I hope you enjoy it as much as we do. I must admit that I rarely measure when making this, but instead taste as I go. However, I did measure it once in order to record it for posterity (and the blog of course!) Enjoy!
*Also I must add that my husband does not really like Chinese food, stir fry, or a lot of vegetables for that matter, but he LOVES this!

Thai Peanut Stir Fry
1/2 cup (or less) vegetable oil
1/4 cup soy sauce
3 cloves garlic, crushed
1 Tbs. white wine vinegar
2 Tbs. brown sugar
3/4 tsp. red chili flakes (more or less depending on the level of heat you want)
1/4 cup + 1 Tbs. crunchy peanut butter
1 lb. stir fry beef ( I often cheat and use stew meat with any extra fat cut off)
3-4 cups chopped veggies: I always use broccoli (fresh or frozen), carrots, and green beans (fresh or frozen) I also like cauliflower, snow peas, and onion (sliced into very thin strips)

Mix the first 7 ingredients. If you used less oil you may need to add a little at a time until you get a smooth consistency. Taste it and add more brown sugar or chili flakes depending on your preference. Set aside.
Cook the beef (I suppose you could use chicken, but in my opinion beef is far superior with these flavors) in a little oil in a large frying pan with a lid. Once beef is cooked, add veggies and 2-3 Tbs. water (less if using frozen veggies). Cover and let veggies steam for 5-6 minutes, until tender. Carefully remove the lid and stir in the sauce. As the sauce heats up it should coat all the meat and veggies evenly. Cook until everything is evenly coated and heated through. Serve over rice.