Mix salmon and lime juice in a glass bowl. Let stand, stirring occasionally, until salmon is opaque and slightly firm to the touch, about 30 minutes. Meanwhile, mix remaining ingredients except tostada shells in another bowl; set aside.
Drain all but about 3 tbsp. lime juice from salmon. Mix salmon with reserved tomato mixture. Serve with tostada shells.
*Find small tostada shells in well-stocked Latino markets.
Wine pairing: Ceja 2012 "Bella Flor" Dry Rosé of Syrah. Beautifully crisp, this pink handles the tangy citrus of the ceviche, and its bright red fruit tames the chiles and sets off the wild salmon.