If we sort all vertices $v \in V$ by decreasing of their exit moment $tout[v]$ then the first vertex $u$ is going to be a vertex from "root" strongly connected component, i.e. a vertex that no edges in a condensation graph come into. Now we want to run such search from this vertex $u$ so that it will visit all vertices in this strongly connected component, but not others; doing so, we can gradually select all strongly connected components: let's remove all vertices corresponding to the first selected component, and then let's find a vertex with the largest value of $tout$, and run this search from it, and so on.