Thaw the frozen shrimp quickly under cold running water and pat them thoroughly dry with paper towels.
Finely mince the garlic and chop the fresh parsley and cilantro.
Heat the extra virgin olive oil in a large skillet over medium-high heat.
Add the minced garlic to the skillet and sauté for 30 seconds until fragrant but not browned.
Add the shrimp to the pan in a single layer and season with sea salt and black pepper.
Cook the shrimp for 2 to 3 minutes per side until they are pink and opaque, then stir in the fresh parsley.
Warm the corn tortillas in a separate dry skillet or directly over a low gas flame until they are soft and pliable.
Shred the green cabbage and thinly slice the avocado.
Assemble the tacos by placing a portion of shredded cabbage on each tortilla, followed by the garlic-herb shrimp.
Top with avocado slices and fresh cilantro, and serve immediately to maintain freshness.