1. In a small skillet, saute onion in oil until golden brown; cool slightly.
2. Unroll crescent dough and separate into triangles. Please note: there will be two extra triangles that may be used to make dinner rolls.
3. Spread 1 teaspoon of mustard on each triangle, divide onions equally and place one link on the wide end of each triangle. Carefully roll-up.
4. Place on an ungreased baking sheet, bake at 350°F for 15-18 minutes or until golden brown.
5. Serve hot.