Lighter Seven-Layer Dip

2 pounds ripe tomatoes (5-6 medium), cored, seeded and chopped
6 scallions, 2 minced and 4 with green parts sliced thin (white parts discarded)
5 tablespoons plus 2 teaspoons fresh lime juice (about 3 limes)
2 jalapeno chiles, stemmed, seeded and minced
1 15-ounce can black beans, drained but not rinsed
2 garlic cloves, minced
3/4 teaspoon chili powder
1 1/2 cups low-fat sour cream
1 tablespoon minced canned chipotle chiles in adobo sauce
2 ripe avocados, halved, pitted and cubed

1. Place tomatoes in a strainer set over a bowl, sprinkle with ½ teaspoon salt, and let drain 30 minutes. Discard liquid. Stir in the minced scallions, 2 tablespoons lime juice, cilantro and jalapeños. Season to taste and set aside.

2. Pulse 2 teaspoons lime juice, beans, garlic and chili powder in a food processor to a chunky paste. Set aside.

3. Whisk the sour cream and chipotles together in a bowl and set aside.

4. Combine the remaining 3 tablespoons lime juice, avocados and ¼ teaspoon salt and mash until smooth. Season to taste.

5. Spread the bean mixture evenly over a serving platter. Spread with avocado mixture, then sour cream, and top with tomato. Sprinkle with scallions.