Start by rubbing the bottom and the inside of a saucepan or a small pot with the garlic clove halves.
Add the beer and place on a stove over medium heat.
While waiting for the beer to start simmering, mix together the feta (crumble it with a fork first), ricotta, butter and flour.
Once the beer begins to simmer, allow it to reduce a bit - for 2 to 3 minutes. Slowly start adding the cheese, butter and flour mixture and stir slowly until well incorporated.
Add the oregano and give a final stir.
Remove from stove and pour into a preheated fondue pot.