I almost never make sauce from scratch.
You know that brown stuff that’s stuck to the pan after you sear meat or stir fry meat?
That’s called fond.
Add a little water, heat and stir to dissolve the fond, and add a little pre-dissolved cornstarch,i.e. a slurry, to thicken the boiling broth to make gravy.
It usually tastes just fine as is, but you can add spices, wine, sugar, salt or whatever.