Stefan Mandel has won the lottery 14 times. He never disclosed the recipe he called combinatorial condensation, which enabled him to hit the Romanian lottery jackpot in the early phase of his betting career. Combinatorial condensation is frequently mixed up with another strategy known as buying the pot, which Stefan Mandel was pursuing later on. On occasion, he dropped a few hints on combinatorial condensation. The hints are applied in this presentation to narrow down and assess his initial recipe. The underlying theory resembles what a weekend mathematician, as he once referred to himself, may have encountered in the 1960s. The size of actual covering designs and the associated efforts allow the following hypothesis: Stefan Mandel most likely pioneered in constructing a (15, 6, 5) covering design with paper and pencil many years before researchers modeled such topics on computers and published about it. Calculations indicate that he took considerable risks that his method might fail: he didn't fully utilize all the lottery numbers, but limited himself to a subset. The risks explain why he later changed his strategy from combinatorial condensation to buying the pot.