In a small bowl, combine garlic, soy sauce, Sriracha, 1 Tbsp lime juice and agave. Stir to combine. Add the shrimp and toss to coat. Allow the shrimp to marinade for at least 30 minutes before cooking.
Pour enough oil in a skillet to reach approximately 1/2-inch to 1-inch deep. Heat over medium-high heat. Once the oil is hot, fry the tortilla rounds in batches of 5 or so, depending on the size of your pan. Make sure you don’t overcrowd the pan. Fry the rounds for approximately 15 to 20 seconds per side, until golden. Remove to a paper towel-lined plate and season with salt. Set aside.
In the bowl of a food processor or blender, combine avocado, sour cream, juice of 1/2 lime, cilantro, 1/2 tsp salt and pepper. Puree until smooth. Set aside.
Heat a medium skillet over medium heat. Remove the shrimp from the marinade and cook until pink and cooked through, approximately 30 seconds per side.
To assemble the mini tostadas, spread each round with approximately 1 to 2 tsp of avocado crema. Top each with one cooked shrimp and garnish with cilantro leaves. Serve warm.