This is a pretty good version of the dipping sauce that Father and Sons restaurant in Ottawa serves with their sweet potato fries.
1 cup mayonnaise
1/2 teaspoon chili powder
1/2 teaspoon ground cumin
1 clove garlic, minced or run through a press
Kosher salt and freshly ground black pepper
In a bowl, mix together the mayo, chili powder, cumin, garlic and a little salt and pepper to taste.