Make the dressing: Pulse the mayonnaise, Sriracha, lime juice, sugar, 1/4 cup cilantro and 1 tablespoon water in a mini food processor until smooth. (Or finely chop the cilantro and mix with the rest of the ingredients in a bowl.)
Place the shrimp in a bowl and toss with 2 tablespoons of the dressing; set aside. Roughly chop the remaining 1/2 cup cilantro. Toss with the coleslaw mix, mango, red onion and the remaining dressing. Season with salt.
Heat the vegetable oil in a large nonstick skillet over medium-high heat. Add the shrimp and cook, stirring occasionally, until opaque, about 3 minutes. Transfer the shrimp to a plate.
Warm the taco shells as the label directs. Fill the shells with the shrimp and some slaw. Serve with the lime wedges and more Sriracha. Refrigerate any extra slaw for up to 3 days.