Creamy Dijon-Dill Sauce

I usually serve this with the garlic lemon-pepper asparagus, when I have time to make it and I'm feeling lackadaisical about calorie counting.

2 green onions, chopped
2 tbs butter
1 tbs corn starch
1 c milk
1/2 c mayonaise
Dijon mustard
salt and pepper to taste
1 tsp each, dried thyme and dill

Melt butter on stovetop, add green onions and cook until soft. Add cornstarch and stir until a thin paste forms. Pour in milk and whip until mixture thickens. Add mayonaise and dijon mustard*. Stir in salt, pepper, and herbs.

* I am not sure how much Dijon mustard I normally use... maybe 3 tbs? I just add a bit at a time until it tastes right.