We have two tips for you today. One is a grand old meat-and-potatoes restaurant where the steaks are super-thick and butter-knife tender. The other is a jiffy mix for cookies that are see-through thin and brittle-crisp. We found these two contrasting (but complementary) delights on a recent trip through Minneapolis.

First, the beef: It is at Murray's Restaurant, now run by Patrick and Tim Murray, son and grandson of Art and Marie Murray who opened the Red Feather Restaurant in north Minneapolis in 1933 and became locally famous for their giant steaks. Thirteen years later, the Murrays moved their business downtown, and it has since become a beacon for meat eaters throughout the Midwest. They serve all the usual shapes and sizes of steak at Murray's, most of them simply cooked but seasoned with a special blend of spices, ranging up to the top-of-the-line cuts that include a nearly 2-pound strip steak (for two) and a behemoth known as the "golden butter-knife steak," costing more than $100, serving four hungry carnivores.What we like about Murray's, in addition to the meat, is how old-fashioned luxurious it is. Ornate iron chandeliers hang above the tables and drapery bunting festoons the walls and windows. Table linen is rosy pink. It is a dining room that is supremely comfortable - and the dinner they serve is guaranteed to satisfy anyone who likes a well-mixed cocktail followed by a juicy slab of beef with a heap of luscious au gratin potatoes on the side and a big wedge of lemon ice-box pie for dessert. Our recipe for au gratin potatoes, an unimprovable classic as served at Murray's, follows.

Now, on to those wondrous cookies we also found in Minneapolis. They are known as Lacey Susans, and the motto that accompanies the bag of cookie mix says, "Cookies can never be too rich or too thin." We were clued into them by Sue Zelickson of WCCO Radio's "Food Finds" show, who gave us a bag of mix to take home and try. Sue invented Lacey Susans more than 20 years ago, but only recently decided to package the formula and sell it through a firm called Canterbury Cuisine, which sends all the cookie profits to the National Down Syndrome Congress.

Lacey Susan are chocolate chip cookies, of the kind sometimes known as Florentines, and they are so thin that you can literally see through them, with each chocolate chip standing up three or four times higher than the brittle-thin cookie itself. What is truly wondrous about them, beyond their irresistible butter-chocolate flavor, is that they are just about the easiest pastry you will ever bake. The ingredients are 1 bag of mix, 1 stick of butter and 1 egg: Blend them all together, drop the dough in little blobs onto a cookie sheet and bake. That's all there is to it! No one would ever believe that cookies so fine and fancy came from a bag. To order your own mix, call or write: Canterbury Cuisine, Box 2271, Redmond, WA 98073-2271; 1 (800) 733-6663. Now available! Nearly 200 of the most-requested recipes from this column, all in one book, "A Taste of America." It includes Jane and Michael Stern's favorite restaurants, as well as photos from their coast-to-coast eating adventures. Available in paperback, it can be ordered by sending $9.95 plus $1 for postage and handling to Taste of America, in care of the Deseret News, P.O. Box 419150, Kansas City, MO 64141.1991, Jane and Michael Stern

(Universal Press Syndicate)

Au Gratin Potatoes

3 tablespoons butter

3 tablespoons flour

1 cup whole milk, warmed

salt, black pepper, cayenne pepper

4 egg yolks, beaten

2/3 cup shredded cheddar cheese

8 cold, boiled potatoes

1/2 cup buttered breadcrumbs\ Preheat oven to 400 degrees. Butter a 9-inch-square ovenproof dish or baking pan.

In a small saucepan, melt butter over low heat. Sprinkle in flour and stir constantly 2 to 3 minutes. Stir in milk and continue stirring until mixture thickens. Bring to simmer but do not boil. Remove from heat and cool to tepid. Season with salt and peppers to taste. Beating constantly, beat in egg yolks, then cheese.

Slice potatoes about 1/4 inch thick and layer them in the prepared baking pan, alternating with the sauce, making sure the top layer is sauce. Sprinkle this with the crumbs and bake 10 to 12 minutes, until bubbling hot.

Serves 4.