In large skillet pour water to halfway up sides. Bring water to simmering (bubbles break surface). One at a time break an egg into measuring cup. Hold lip of cup close to water; carefully slide in egg, allowing each equal space in pan. Simmer, uncovered, 3 to 5 minutes, until whites are set and yolks begin to thicken but are not hard.
Meanwhile, in second skillet cook leeks and grapes over medium heat in 2 tablespoons hot olive oil for 4 minutes, just until leeks are tender and grape skins burst. Remove from heat. Add vinegar. Sprinkle salt and pepper. With slotted spoon transfer eggs to toast. Serve with greens, leeks, grapes, and cheese. Serves 4.