1. To make the chicken: Rub the chicken thighs with cumin and a generous sprinkling of salt and pepper.
2. In a large, high-sided skillet, heat the olive oil over medium-high heat. Add the chicken thighs and brown the skin, 7 to 10 minutes per side.
3. Add the 2 cups of chicken stock. Bring to a boil, then cover and reduce the heat to medium-low; allow the stick to simmer 20 minutes.
4. Add the chopped mint and the sliced or chopped olives. Continue cooking 15 to 20 minutes, or until the chicken is tender.
5. Remove the lid, increase the heat to high, and reduce the sauce 3 to 5 minutes, until slightly thickened. Add additional salt if desired.
6. To make the couscous: In a medium saucepan, heat the 2 cups of chicken stock until just boiling, add the couscous and salt and cover. Remove from the heat and let stand 5 minutes. Fluff with fork.
7. Serve the couscous on a plater with the chicken on top. Spoon the sauce over it and garnish with mint leaves.