Lentils with Cucumbers, Chard, and Poached Egg

Bring about 2" water to a boil in a large saucepan; reduce heat so water is at a gentle simmer and add vinegar, which helps the whites coagulate. Crack an egg into a small bowl, then gently slide it into water. Repeat with remaining eggs, waiting until whites are starting to set before adding the next one (about 30 seconds apart). After about 3 minutes, whites should be set and yolks still runny. Using a slotted spoon, transfer eggs to paper towels as they are done. Combine lentils, scallions, dill, lemon zest, and 1 tablespoon lemon juice in a medium bowl; season with salt and pepper. Toss cucumbers with 1 tablespoon za'atar and remaining 1 tablespoon lemon juice in a small bowl; season with salt and pepper. Heat oil in a medium skillet over medium. Add Swiss chard by the handful, tossing and letting it cook down a bit before adding more, and cook until tender; season with salt and pepper. Stir in garlic, if using, and set aside. Divide lentils among bowls and top each with some chard, cucumbers, a few dill sprigs, and a poached egg. Sprinkle with more za'atar.