1. Warm oil in a large skillet over medium-high heat. Add onion and jalapeño and cook, stirring often, until softened, 3 to 5 minutes. Add garlic; sauté 1 minute. Transfer half of mixture to a food processor.
2. Add corn and bell pepper to the skillet with remaining cooked onion mixture. Stir over medium-high heat until corn is slightly cooked and warmed through, about 3 minutes. Season with salt and pepper.
3. Add beans to processor; pulse to blend. Add half of lemon juice and 2 Tbsp. warm water. Process until smooth. Season with salt and pepper. Spread over bottom of a deep-dish pie plate. Spread corn mixture on top of bean mixture.
4. Mash avocado with remaining lemon juice and cilantro. Season with salt and pepper. Spread over corn mixture. Mix sour cream, yogurt and chipotle in a small bowl and spread over avocado layer. Spread salsa over sour cream mixture; top with cheese and scallions. Serve at room temperature.