Mix tempura batter according to the box directions. In a small sauté pan, add corn and toast lightly. Add shrimp and cook until opaque, about 2-3 minutes. Add ancho chili powder and ground red pepper. Reduce heat to low. Add garlic and cook until fragrant. Add onion powder, cilantro and salt. Add about 1 cup of tempura batter and mix to coat. The consistency should be chunkier than liquid.
Heat olive oil on a griddle, large wok or sauté pan over medium-high heat. Add about 1/4 of the batter into the oil and fry until golden on both sides.
In a small mixing bowl, combine all ingredients. The sauce can be placed in a squirt bottle or served on the side.