Grate the sharp cheddar cheese into a bowl.

In another bowl, mix the grated cheese with cornstarch until well coated.

In a medium saucepan over medium heat, add the beer and minced garlic; stir until simmering.

Gradually add the cheese mixture while stirring continuously until melted and smooth.

Stir in the lemon juice and mustard powder until fully combined.

Serve warm in a fondue pot or serving bowl with dippers like bread cubes and vegetables.