Preheat oven at 200°C. Cut the baguette into ½-inch slices.Mix the olive oil and garlic to make a paste and brush over the baguette slices. Bake in the oven for 5 minutes.
In a medium-sized mixing bowl combine the onions, sumac and olive oil, and allow to sit for about 10minutes. Remove the zaatar leaves from the stem, wash and thoroughly dry. Add the zaatar leaves, cherry tomatoes, feta cheese and lemon juice to the onion mix, and season with salt and pepper.
On each slice of toasted baguette add a spoonful of the zaatar mix and serve.