In a food processor, add the jalapeños, cilantro, mayonnaise, sour cream, avocado, and lime juice. Blend until smooth, then refrigerate until needed.
Brush the tilapia fillets with olive oil and grill over medium heat for 2-4 minutes per side, until cooked through and flakey.
Heat tortillas on grill and spread 2 tbsp. of sauce on each warm tortilla.
Place 1/2 of a fillet in the center of each tortilla and add shredded cabbage. Fold the tortilla and top the taco with salsa, sour cream, and a splash of lime juice.