Based on an approximate modeling of scrape-off-layer (SOL) dynamics and edge turbulence, it is shown that a new type of limit cycle oscillation (LCO) or one-step L–H transition can be triggered from the outer-well E × B flow shear originating from the SOL region. From its close relevance to SOL properties, this model appears to provide a possible explanation of the L–H threshold power dependence on magnetic or divertor geometry.