Preheat oven to 350 degrees.
In a large saute pan, over medium high heat, saute the garlic cloves in olive oil with the blackening spices. Place tomatillos, scallions, 1 clove of garlic, cilantro, jalapeno, and salt and pepper in a food processor and puree. Set aside.
In a large bowl whisk together lime juice and extra virgin olive oil and season with salt and pepper.
Place crabs in deep glass dish and pour milk over them. In an another dish place flour and dredge the crabs through to cover.
In a large saute pan, over high heat, saute crabs until golden brown and crisp.
Remove crabs and drain on paper towels.
Mix black beans, arugula, and vinaigrette and season; portion mixture equally on plates. Top bean mixture with a crab and drizzle with garlic tomatillo sauce. Garnish with sliced red onions, avocado, chives, and spiced garlic cloves.