Rinse green beans and trim off stem ends; cut beans into about 3-inch lengths. Rinse, stem, and seed bell pepper; cut lengthwise into thin slivers about 3 inches long.
Set a 10- to 12-inch frying pan over medium-high heat. When pan is hot, add green beans and 3 tablespoons water; cover and cook until beans are bright green, 3 to 4 minutes. Add 1 teaspoon sesame oil, bell pepper, and garlic; stir until pepper begins to soften, about 2 minutes. Add garbanzos, white beans, green onions, and hoisin vinaigrette. Stir until garbanzos and white beans are hot, about 2 minutes. Stir in remaining 2 teaspoons sesame oil. Pour into a serving bowl and sprinkle with cilantro.
Hoisin vinaigrette. In a blender or food processor, whirl 1/3 cup rice vinegar, 1 1/2 tablespoons hoisin sauce, 1 1/2 tablespoons water, and 2 teaspoons chopped fresh ginger until smooth. Makes about 1/2 cup.