Let's all have a collective AAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHH
You actually made some great choices for dinner out. As to what the veggies were sauteed in, I know the asian restaurants near me use oil for sauteed foods, not butter. When in doubt, NEVER be shy about asking! It's your health! Look at it this way - if you were a diabetic and HAD to know what was in the food you were eating so you could take insulin, you wouldn't hesitate. Think of the dietary needs of IP the same way. The veggies were probably fine, and unless the beef was marinated in sugar and a gluten-heavy soy sauce, it was probably ok too.
RE: Ketosis - that has to do with the carbs you eat, not fats. So even if there was butter on the veggies, it would not have an effect on ketosis (though a lot of extra fat would affect your weight loss because of the extra calories). There's no "Magic" number or line in the sand for when you have eaten enough carbs to take you out of ketosis - some people are very carb sensitive and it doesn't take much. Others can tolerate more.
The bottom line is, don't stress about it. Just learn from this experience, and run with your clean slate in the morning