Serves: 2 1/2 cups hummus (10 1/4-cup servings)
Place the chickpeas, garlic, and sea salt in the bowl of a food processor. Process for 15 to 20 seconds. Stop, scrape down the sides of the bowl, and process for another 15 to 20 seconds.
Add the lemon juice and water. Process for 20 seconds. Add the tahini. Process for 20 seconds, then scrape down the sides of the bowl. With the processor running, drizzle in the olive oil.
To serve, transfer the hummus to a bowl and drizzle with additional olive oil and sprinkle with sumac, to taste, if desired.
For the Slow Cooker Chickpeas:
Place the water, chickpeas, and baking soda in a 2 1/2-litres slow cooker. Cover and cook on high heat for 4 hours, or on low heat for 8 to 9 hours, or until tender. Drain and serve immediately, or use in desired dish.