In a pot, bring 400 ml of water to a boil. Stir in the couscous, cover, and remove from heat. Let it sit for 5 minutes, then fluff with a fork.
In a large skillet, heat olive oil over medium heat. Add the diced beef and season with salt, pepper, and cumin. Sauté for about 7-10 minutes, until browned and cooked through.
In a mixing bowl, combine tahini, lemon juice, lemon zest, and minced garlic. Whisk until smooth. You can add a little water if needed to reach your desired consistency.
In the pot with couscous, gently fold in the cooked beef, diced cucumber, and chopped lettuce. Drizzle in the tahini mixture and toss until everything is evenly coated.
Divide the beef couscous mix into serving bowls. Top with chopped cilantro and any additional toppings like sliced radishes or extra lemon wedges as desired.
