Wash and dry all produce. Bring 1 cup water and a pinch of salt to a boil in a small pot. Trim green beans and cut into 2-inch pieces. Strip leaves from rosemary sprigs and chop until you have 1/2 tsp. Roughly chop olives and garlic. Halve lemon.

Add couscous to boiling water. Cover, remove from heat, and let stand until water is absorbed, 5 minutes. Meanwhile, in a large bowl, season chicken all over with salt and pepper. Sprinkle with flour and toss to coat (not all flour will stick).

Heat a large drizzle of olive oil over medium-high heat in a large, high-sided pan. Add chicken in a single layer and cook just until starting to brown, 2-3 minutes per side. (TIP: You may need to cook chicken in batches.) Remove to a plate.

In same pan, heat a drizzle of olive oil over medium heat. Add green beans, garlic, and rosemary and toss until garlic is fragrant, 1 minute.

Stir diced tomatoes, half the chicken demi-glace, and 1/4 cup water into pan. Scrape up any bits on bottom. Bring to a simmer over medium-high heat. Return chicken to pan and toss to cover in sauce. Simmer until chicken is cooked through and sauce thickens, 4-5 minutes. Remove from heat. Squeeze a little lemon juice into pan (to taste).

Fluff couscous with a fork and add a drizzle of olive oil and a squeeze of lemon. Season with salt and pepper to taste. Divide couscous between plates and top with chicken, green beans, and sauce. Garnish with olives.