Heat the olive oil in a large pan over medium-high heat. Add the chopped onion and saute until softened, about 3 to 4 minutes.
Stir in the minced garlic and cook for 30 seconds until fragrant.
Add the ground beef and cook, breaking it up with a spoon, until browned.
Add the cumin, coriander, turmeric, paprika, sumac, salt, and pepper. Stir well and cook for 5 minutes.
Pour in the water, reduce the heat to low, cover and simmer until the mixture is slightly saucy, about 5 to 7 minutes.
In a small bowl, whisk together the yogurt, tahini, lemon juice, salt, and pepper until smooth.
Divide the rice among bowls. Top with the spiced ground beef and chopped vegetables.
Drizzle with the yogurt tahini sauce and serve immediately.