This is an incredibly dangerous practice that was invented in the 90s to sell poorly made fake absinthe. The “Czech” method was never used during the “Belle Epoque” era when absinthe was popular, nor was it invented in the Czech Republic. Furthermore, high-proof liquor and fire should never be around each other. Lastly, the burned sugar cube ruins the flavor profile of a well crafted absinthe. Performing the Czech method is akin to shaking a bottle of Champagne.
Please, don’t do this…