The West Village’s Alfama, one of the city’s top Portuguese restaurants, has lost its chef and is headed into new territory. Luis Caseira’s last day in the kitchen was this past Thursday, and he has been replaced with executive sous-chef Mark Twersky. (Caseira, we’re told, left to return to Portugal to be with his 11-year-old son.) Alfama’s loss may turn out to be our gain, as Twersky, a veteran of Per Se’s kitchen, should liven up what has been a fine but somewhat stodgy restaurant. The new menu, which will reflect Twersky’s attempts to create a more contemporary kind of Portuguese cooking using ingredients from Africa and Asia, among other places, will be in place by June 21, Tarcisio Costa, Alfama’s co-owner, tells us. “We’ll still have our traditional dishes, but Mark will also create dishes with a more modern approach, based on the many world cultures that are a part of Portugal’s history.” So in case you never connected Mozambique with Portugal, a pleasant surprise might be in the offing.