You could try beurre manié. I've never done it because I always make a roux. But I think we must have different definitions of roux because what I call a roux is the work of a few minutes only.

If you want to use flour, Wondra really doesn't make lumps. It's convient and I use it often.

I like arrowroot starch for a sauce and tapioca starch for things like pie. Just don't get the ridiculously priced little bottles. Bob's as well as other fine purveyors have inexpensive pound bags if you have a canister. I know exactly what you mean about the cornstarch. There's a pretty good Chinese restaurant a friend likes, but the soups are gloopy beyond edibility!

I may be using the wrong term for roux? I put flour in a pan, no oil or liquid just dry flour, cook over low heat, stirring often, until the flour turns a medium brown . . . I'd prefer darker but always run out of patience.

“Roux” implies fat is involved. You’re just making browned flour. It would probably brown faster if fat was involved.

Making a largish batch of browned roux in the oven, then dividing and storing in portions in the freezer might work for you.

In restaurant kitchens I used beurre manie frequently because it is fast and straightforward.

Back in the 80’s we made plenty of reduced in the pan sauces. Some kitchens did keep demiglace on hand (very nice) but we also used cream. If you are skilled and the timing is right, you can do a butter mounted sauce.

Potato flakes are great in soup but I’ve never tried in a sauce.

Browning flour in the oven is pretty common in the south. Or at least so I've read. It's hard to get a chocolate roux, w/out burning it, for Gumbo so many use the oven.

I use clarified butter so I don't have to worry about it burning on higher heat. I usually clarify a lb at a time and then keep it near the stove. I cut back the amount of butter by 1/4 when using it. You can also take it further to a brown butter which will add even more flavor.

A long time ago, I made a lot of sauces that started with a blond roux, and I could make them with oil. It has a lighter feeling than butter. The fat is necessary if you're going to bind the sauce. The toasted flour for thickening sounds interesting. I forget what it's called, but you can do the jar thing. Put the flour in a small jar with some of the liquid and shake like the dickens until all the flour is moistened and there are no lumps, then add the wet and lump-free to the sauce.

I find if you toast the flour, it never clumps, no ”floury” taste to cook out, thickens effectively, and you can choose the fat by desired flavor.

I’ll try these other things. Beurre manie sounds fast but gets your hands all messy?

In a perfect world, you could get the gravy or sauce to exactly the right flavor and then do the cooking equivalent of snapping your fingers and presto it is thickened exactly as much or as little as you want.

I always just thicken with flour and water/milk. Put some water or milk into a bowl or I usually just use my measuring cup and then however much flour I need to thicken the amount of gravy and whisk it together until smooth then I pour it into the hot liquid and stir until thickened.

I once, quite a long time ago, froze little packets of rubbed in flour with butter. Rubbed in meaning as you would start to make a shortcrust pastry. I recall they were handy to just throw into something that needed thickening. But really as mentioned, a roux takes very little time.

Modern cooking would thicken sauces more by reduction today but I think that flour has its place. A proper velouté needs flour to give that lovely velvety mouth-feel.

If I make a sauce for a steak or white chicken meat then I don't want flour but if it's a proper roast dinner then I use flour to make the sauce more "gravy"-like. A béchamel has a lovely creamy feel that can only come from flour. I've tried these substitutes that use yogurt and egg yolks but it's not the same.

I make velouté sauce more than any other and have never felt that cooking the flour in butter (or fat) took that long.

If you want something faster, you can add potato starch or potato flakes (which is what I use frequently) to thicken a liquid into a sauce.

If your roux is just browned flour, I see no reason why you would need to freeze it to keep. I would think it needed nothing more than it did before you browned it since it is nothing but flour.

I dont do a roux very often . That can add so much fat to something that I opt out of it, mostly. I strive to keep our meals in the lean range. So many old culinary tricks really are more suited to those who really need those calories, and that is not us at this age. Hubs is very physically fit and you would never suspect that he has the major health problems that he has, until you look closer. High fat foods are for an occasion. And gravies and roux are pretty heavily loaded.