Combine Sriracha, olive oil, soy sauce, garlic, cilantro, sugar and lime juice in a bowl. Add shrimp and salt and pepper. Pour into large plastic bag and marinate for at least 1 hour or overnight. Place shrimp on skewers and set aside.
Heat gas grill or indoor grill pan. Place shrimp on grill and cook 2-3 minutes per side until pink. Remove from skewer and set aside.
Brush corn with olive oil and place on grill next to shrimp. Turn corn occasionally until cooked and grill marks are all around the corn. Set aside to cool.
Make the vinaigrette: Combine olive oil, 2 tablespoons of lime juice, cilantro, garlic, and serrano pepper in a blender or food processor and blend. Taste and adjust seasonings, adding more lime juice if desired.
Place purple cabbage, red pepper, and red onion in a large bowl. Cut cooled corn off the cob and add to the bowl. Add shrimp and dressing and toss to combine. Garnish with avocado, queso fresco and cilantro. Enjoy!