To make the mango relish: In a medium bowl, gently toss the mango, red onion, garlic, jalapeño, and cilantro with 1 tablespoon olive oil and 1 tablespoon lemon juice. Season to taste with salt and pepper. Set aside until ready to serve.
Make the avocado cream: Place the avocado, yogurt, lemon juice, and cumin in the bowl of a food processor or blender. Blitz until smooth and creamy; season to taste with salt and pepper. Transfer to a bowl, and set aside until ready to serve.
To finish & serve: Season the shrimp generously with salt and pepper. Heat a large skillet over medium-high heat, and add the olive oil. When the oil is hot and shimmering, add the shrimp and garlic. Sauté the shrimp until they’re pink and just firm, about 3 minutes.
Spoon a dollop of the avocado cream onto each warm tortilla, and top with the shrimp. Garnish with spoonfuls of the mango relish, and serve warm with wedges of lemon.