POLITICS CHANGED and so did pistachios. Throughout history, countries such as Iran, Turkey and Syria have supplied most of the world's pistachio nuts. The United States, however, has slowly been eating into this Middle Eastern monopoly. In 1982, the United States contributed a record 32 percent to worldwide production, and this year, according to recent U.S. Department of Agriculture estimates, domestic pistachio production is expected to be up sharply.

How did we crack this nut? Interestingly, the 1980 Iranian hostage crisis and the subsequent one-year embargo on imported goods had nothing to do with the growth of the American pistachio industry. It was a coincidence.

According to the California Pistachio Commission (members of which grow the majority of domestic nuts), an aqueduct built in the 1960s made water available to lands that had not been viable for cultivation previously. In addition, said Chris Wyatt of the trade association, in the 1970s tax shelter benefits were given to growers interested in planting pistachios.

It takes about 10 years for a tree to produce commercially marketable pistachio nuts, according to Wyatt. At the time the United States severed relations with Iran, California growers saw the first impact of their plantings; the figures for the 1979-80 harvest jumped to a record 17.2 million pounds.

The California nuts are slightly larger than the imported nuts and only 50 percent of them are being artifically colored with red dye. U.S. processors dye the majority of imported pistachios after they reach this country, said Wyatt.

The reason is esthetics: Pistachios, which hang in grapelike clusters, are covered with a rose-colored skin. If the skin is not removed within 24 hours of harvesting, the whitish shells become mottled and stained.

In fact, Americans have been so brainwashed that in taste tests held by the California Pistachio Commission, hard-core pistachio eaters preferred the taste of the red-dyed nuts when presented with two identical nuts, one colored, one not, said Wyatt. She said the commisssion is convinced, however, that the new "natural-oriented" pistachio eater will prefer the uncolored variety. For traditional eaters, though, half of California's crop will remain red.

The following Express Lane meal uses shelled pistachios as a coating for chicken breasts. (They are also good in stuffings, stir-fried vegetables, salads and pie crusts, in addition to the traditional Middle Eastern lamb dishes, pastries and desserts and Italian mortadella.) You will need butter and flour already at home and, for those for whom a pistachio isn't a pistachio unless it's red, lots of soap and water.

EXPRESS LANE LIST: pistachio nuts, chicken, eggs, honey, dijon mustard, broccoli, lemons. PISTACHIO CHICKEN WITH HONEY-MUSTARD SAUCE (4 servings) 4 boneless chicken breasts 1/4 cup butter, melted 1/3 cup flour 2 eggs, beaten 1 cup finely chopped pistachios For honey-mustard sauce: 1/2 cup dijon mustard 3 tablespoons honey

Dip chicken breasts in melted butter to coat. Place flour in plastic bag and place chicken breasts in bag, one at a time, shaking to coat. Shake off any excess flour and dip each breast in egg. Shake off any excess egg and dip in plastic bag filled with chopped pistachios. Shake to coat. Place chicken breasts in baking dish and cook in a 350-degree oven for about 30 minutes. To make honey-mustard sauce, mix together mustard and honey. Serve alongside chicken breasts with steamed broccoli sprinkled with lemon juice.