Heat oil in heavy large saucepan over medium-high heat. Add onion, jalapeño, garlic and cumin; sauté until onion and jalapeño are tender, about 10 minutes. Cut corn kernels from cobs. Add corn to pot. Stir in broth. Cover and simmer over medium-low heat until corn is very tender, about 20 minutes. Transfer to processor or blender and carefully purée. Add enough milk to thin to desired consistency. Return to pot; stir to heat through (do not boil). Season to taste with salt and pepper. Serve in bowls and garnish with cilantro.