In a large bowl, add shrimp, garlic, salt and pepper and half of the olive oil. Toss well to coat evenly. In a sauté pan, heat the remaining olive oil over medium heat. Add the shrimp mixture and sauté for about 2 minutes each side. Set it aside.
Place the cooked quinoa in a large bowl and add red cabbage, red bell peppers and black beans.
Pour the homemade vinaigrette dressing over the quinoa salad and stir to combine.
Add the shrimp and garnish with green onions before serving.