1Heat oven to 425°F. Cut each potato crosswise into about 4-inch chunks, then cut lengthwise into 1/2x1/2-inch strips.
2In large resealable food-storage plastic bag, mix Cajun seasoning and cumin. Add potatoes; toss until evenly coated. In ungreased 15x10x1-inch pan, arrange potatoes in single layer.
3Bake 35 to 40 minutes, turning once, until potatoes are lightly browned and tender. Meanwhile, in small bowl, mix all sauce ingredients. Serve sauce with fries.