Cook potatoes in boiling salted water. Drain. Remove skin. Press through ricer or food mill. Should have about 5 cups or 1 1/2 pounds.
Combine riced potato and remaining ingredients in a large bowl. Mix well and divide into 15 2-oz. portions. Cover well until ready to use.
Sauté onion, garlic and corn kernels in oil until ingredients are just softened. Remove from heat and stir in meat.
Assembly and frying
Using palm of hand, shape one masa ball into a cup shape.
Place 2 rounded tablespoons (about 1 oz.) meat filling into the cup. Gently press dough together to form a ball wrapping the meat, using water moistened fingers to seal cracks and make a smooth sphere, about 2.25-inch diameter. Repeat with remaining tamale dough and filling*.
*May have about 1 cup leftover filling.
Refrigerate spheres well-wrapped for up to 3 days.
Heat frying oil to 350°F. Fry spheres until deep golden brown, 4-5 minutes until center is 160°F. Serve warm or room temperature with condiments and garnishes.