In glass bowl, add scallops and marinade to cover. Cover bowl and refrigerate; marinate until scallops are opaque throughout, at least 4 hours or up to 16 hours.
Fold in tomato, avocado, cilantro, capers and Salsita; refrigerate until ready to use.
Meanwhile, heat oil in skillet over medium-high heat; cook tortillas in batches until crisp and golden brown on both sides, 1 to 2 minutes. Transfer to paper towel–lined plate to drain.
Top each tostada with scallop ceviche.
Garnish each tostada with sliced jalapeños for a spicy kick.