Heat the olive oil in a large saucepan over medium heat. Stir in garlic, and cook 1 minute.
Stir in rice, salt, cumin, sumac (optional), turmeric, paprika and cayenne pepper. Cook and stir 5 minutes, then pour in chicken stock.
Bring to a boil. Reduce heat to low, cover, and simmer 20 minutes.
Gently mix chick peas, black beans, parsley, and lemon juice into the cooked rice.
Cook another 5 minutes on low heat.
Garnish with whole parsley leaves, tomatoes, a dollop of Greek yogurt and scallions.