Place garlic, green onions, cilantro, lime juice, olive oil and water in a food processor and purée until smooth. Add salt and Greek yogurt and continue to purée until smooth.
In a large bowl, combine the cabbage and 2-3 tablespoons of dressing; toss to combine.
Make the black beans:
In a large fry pan, heat olive oil over medium heat. Add onion and cook, stirring occasionally, until tender, about 5 minutes.
Add garlic and cook for 1 minute.
Add black beans, water and salt. Very lightly smash the beans with a potato masher or fork, leaving small bits. Cook over low heat, stirring occasionally, until the liquid has almost evaporated, about 5 minutes.
Remove from heat, add lime juice and stir to combine.
Make the fish:
Preheat oven to 425 degrees.
Line a baking sheet with foil and place haddock on baking sheet. Drizzle with olive oil and turn to coat.
In a small bowl, combine the cumin, smoked paprika and cayenne pepper. Sprinkle over both sides of fish.
Bake for 8-10 minutes or until fish flakes easily with a fork.
Assemble the tacos:
Using tongs, toast tortillas individually over a gas burner.
Stack one tortilla on top of another. Top with 1-2 tablespoons black beans, a spoonful of slaw, some flaked fish and Feta cheese. Season with salt and pepper to taste.
Notes
You will have extra dressing after making the slaw; store it in an airtight container in the refrigerator for up to a week.
Recipe by Two of a Kind at http://www.twoofakindcooks.com/easy-fish-tacos-with-cilantro-lime-slaw/