1
COMBINE the tomatoes, avocado, onion, cilantro, lime juice, 1/4 teaspoon of the salt, and the pepper in a bowl. Set the salsa aside.
2
BRING 2" of water to a very gentle simmer in a large skillet. Add the vinegar. Carefully break the eggs into the skillet, holding them just above the water level so they slide in without breaking the yolks. Simmer for 5 to 6 minutes, or until the egg whites are firm and the yolks have barely started to set. One at a time, lift the eggs out with a slotted spoon and place on a plate lined with paper towels to absorb excess water.
3
MEANWHILE, coat a large nonstick skillet with cooking spray and heat over medium-high heat. Add the spinach and cook for 1 1/2 to 2 minutes, tossing often, until wilted. Sprinkle with the remaining 1/4 teaspoon salt.
4
ARRANGE 2 pieces of toast on each of 4 plates. Top each half with 1/2 c. spinach. Place 1 egg on top of toast. Spoon 1/2 c salsa over the eggs and serve with 1 Tbsp yogurt. Serve hot.