Authentic Lebanese Fattoush

Ingredients: 1. Water – 1/2 cup. 2. Cornstarch – 1 tspn. 3. Lemon juice – 1/3 cup. 4. Garlic, minced – 2 cloves. 5. Sumac powder – 2 tspn. 6. Salt to taste. 7. Ground black pepper to taste. 8. Romaine lettuce – torn into bite-size pieces. 9. Cucumber (diced)…