Look for crema Mexicana--similar in taste and consistency to crème fraîche--in the ethnic section of your grocery. Or substitute sour cream.
Preheat oven to 375°.
Pierce potatoes with a fork, and bake at 375° for 1 hour or until tender. Cool potatoes slightly.
Cook cumin seeds in a small skillet over medium heat 1 minute or until toasted. Combine cumin seeds and next 6 ingredients (through garlic) in a medium bowl; stir well.
Split potatoes lengthwise, cutting to, but not through, other side. Spoon 1/4 cup corn mixture into each potato. Top each serving with 1 tablespoon crema Mexicana.