Preheat oven to 325 degrees F. In medium bowl combine flour, chives, 1/2 teaspoon salt, and 1/8 teaspoon pepper. In another bowl combine water and oil. Drizzle oil mixture into flour mixture, stirring constantly (dough will appear dry but will come together when gently worked with hands). Form dough in a ball.
On a lightly floured surface roll dough in 12x7-1/2-inch rectangle. Prick all over with fork. Sprinkle with pistachios and cheese; press in nuts. Using a pizza cutter, cut dough in 3x1-1/2-inch rectangles. Transfer to large ungreased baking sheet.
Bake 20 to 23 minutes or until crisps begin to brown. Transfer to wire racks. Cool. Serve crisps with Caper Mustard. Makes 20 crisps.
In small bowl combine mustard; sour cream, capers; and chives.