Add 2 15-ounce cans garbanzo beans, ¼ cup olive oil, 4-5 tablespoons fresh lemon juice, 3 cloves garlic, 1 teaspoon ground cumin, salt, and freshly cracked black pepper to food processor bowl.
Secure lid on food processor. Process ingredients until fully combined into smooth mixture, pausing to scrape down sides of bowl as needed.
Add reserved garbanzo bean liquid in small amounts as needed to thin mixture to desired consistency. Be sure to process mixture well after each addition to ensure liquid is fully absorbed.
When satisfied with consistency, remove lid. Taste hummus and adjust salt and pepper as needed.
When satisfied with flavor, transfer hummus to serving bowl. Cover bowl with lid or plastic wrap and refrigerate hummus at least 30 minutes.
Just before serving, remove hummus from refrigerator and uncover. If desired, garnish hummus with swirl of additional olive oil. Serve chilled with fresh vegetables, pita bread, tortilla chips, crostini, or other dipping vessels of choice.