Marinated Kale Salad

Massage kale with olive oil and 1/2 teaspoon salt in a large bowl, coating all surfaces, about 2 minutes. Let stand at room temperature at least 15 minutes and up to 1 hour.

Rinse onion in a sieve under warm water for 2 minutes. Drain well. Combine onion, sumac (if desired), and sesame seeds in a small bowl. Combine juice, mustard, and garlic in a small bowl.

Add juice mixture and chickpeas to softened kale; toss well. Stir in remaining 1/4 teaspoon salt and pepper. Top with onion mixture.