blackened shrimp tacos

Ingredients

• 2 tablespoons buttermilk
• 2 tablespoons mayonnaise
• 1/2 teaspoon garlic, minced
• 1/2 teaspoon white vinegar
• 2 ounces queso fresco, crumbled (about 1/2 cup)
• 2 teaspoons paprika
• 1 1/2 teaspoons ground cumin
• 3/4 teaspoon garlic powder
• 1/2 teaspoon dried oregano
• 1/4 teaspoon salt
• 1/4 teaspoon dried thyme
• 1/4 teaspoon ground red pepper
• 1 pound medium shrimp, peeled and deveined
• - cooking spray
• 8 - corn tortillas (6 inch)
• 1/2 cup plum tomatoes, diced
• 1 - avocado, ripe, peeled and roughly mashed