Soak quinoa for 30 minutes in cold water, rinsing thoroughly several times in fresh water to get rid of the bitter husks. Discard water after each rinse, and finish by draining through a fine mesh strainer.
After the final rinse, put quinoa in a two-quart saucepan with 1 1/2 cups cold water and a 1/2 tsp of salt. Bring to a boil, turn heat down to low, cover tightly and cook for 15 minutes. When time's up, remove from heat and leave covered for five more minutes. Don't lift the lid.
While the quinoa is cooking, dice the vegetables. Then saute garlic in two tbsp olive oil until lightly browned. Add diced celery and carrots and saute until softened. Add green pepper and lightly saute, then add cumin and coriander and continue cooking for another five minutes.
Fluff quinoa with a fork and transfer to a large bowl to cool. While the quinoa is cooling, whisk together the dressing ingredients.
Gently stir the veggie mixture into the quinoa. Add tomatoes, beans and dressing and stir to combine. Finally, stir in cilantro and scallions.

1 cup quinoa
1 1/2 cups cold water
1 (15 ounce) can black beans, rinsed and drained
2 tablespoon olive oil
1/2 cup diced celery
1 carrot, diced
1 cup fresh green beans, steamed (optional)
2 cloves garlic, minced
1 green pepper, sliced
1 teaspoon cumin powder
1 teaspoon coriander powder
2 tablespoon chopped cilantro
3 or 4 scallions, chopped
1 large tomato, chopped or 1 cup chopped cherry tomatoes
1/2 cup olives, sliced (optional)

Dressing:
2 tablespoon freshly squeezed lime juice
4 tablespoon olive oil
1 teaspoon salt
fresh ground pepper, to taste
pinch of cayenne or chili powder