IN "THE MUPPET MOVIE" Steve Martin plays an incompetent sommelier who offers Miss Piggy and Kermit the Frog what he calls the finest wine Idaho has to offer. He proceeds the twist off the cap, sample the wine and spit it across the room.

Bill Broich, winemaker at Ste. Chapelle at Sunny Slope in southwest Idaho, says, "Please don't talk to me about 'The Muppet Movie'some very good wine, and the bottles all have corks. Ste. Chapelle, in business since 1976, began as an adjunct to the Symms Fruit Ranch. The third-generation business is run by Dick Symms, whose brother Steve is Idaho's junior senator. Broich is a partner in the winery, as well as the winemaker. His introduction to professional wine-making was a bit unorthodox. After making wine at home for years, he and his wife spent a harvest season in the vineyards of France. They all visited Ste. Chapelle in Paris and decided that if they ever built a winery they would use the name and the chapel's architectural style. After his return to Idaho, Broich says, "I bought a load of grapes, borrowed $20,000 from the bank, and went for it."

Those grapes came from the Symms ranch. Soon Broich and the Symmses were partners; today the winery, which resembles Ste. Chapelle, produces 130,000 cases of varietal wine a year. One of the big attractions of the wine is its price. Ste. Chapelle's best chardonnay has more complexity than you would expect for $10. The '83 has a touch of oak and good fruit but is low in acid. Summers in southern Idaho can be too hot for gradual maturation, but usually the sunny days and cool nights produce chardonnay with a clean, elegant finish like Ste. Chapelle's '82.

Severe winters can also be a problem. Winter kill -- damage to exposed portions of the vine -- has historically discouraged th planting of wine grapes in the northwest. However, that has not prevented more than 100 wineries from springing up in the region in recent years or their wines from winning medals in national and international competitions.

Ste. Chapelle's less expensive "chardonnay blanc" is less attractive at $5.50 when compared to comparably priced Sonoma County chardonnay or to Macon-Villages. Ste. Chapelle's riesling and its chenin blanc are deliberately made slightly sweet to accommodate local tastes. The chenin, ($5.50) fermented at very low temperatures, has good fruit and a slight spritz.

The cabernet sauvignon is a pleasant surprise. I found the '82 ready to drink, light in color and body. A bottle of the '83, not yet released, was remarkably forward, with a touch of tannin and a slightly jammy finish. By contrast, the '77 had a hint of cassis in the bouquet, good body and a lively finish.

Whether Idaho can produce great wine depends more on the winemakers' ambition than on any climactic limitations. Ste. Chapelle, which does a thriving side business in T-shirts and wine paraphernalia, will likely continue to produce good commercial wine. Meanwhile, Bill Broich has decided to start his own smaller winery devoted to quality riesling and chardonnay. "I want something to pass on to my kids," he says.

Perhaps we have yet to taste the finest wine Idaho has to offer.