In a medium bowl, combine flour, cornstarch, garlic powder, onion powder, paprika, salt, and beer. Mix well; it will be a thick, glue-like consistency.
Dredge chicken in batter.
Heat oil in a frying pan over medium-high heat. When oil is hot, place chicken in frying pan and fry until golden brown, about five minutes. Carefully flip the chicken over and fry for an additional minute. Remove from pan.
Combine horseradish with silan, mustard, and mayonnaise. Mix well.
