My new favorite Sunday brunch recipe, swiped from epicurious.com :). If you're looking for a total egg-poaching adventure, google Julia Child's instructions for how to poach the "proper" way. It's fun, I promise!
4 (3-inch-wide) portabella mushroom caps, stems discarded
2 plum tomatoes, halved lengthwise
3 tablespoons olive oil
1/2 teaspoon salt
1/4 teaspoon black pepper
1 teaspoon distilled white vinegar
4 large eggs
1/2 teaspoon balsamic vinegar
1 tablespoon finely chopped fresh chives
Brush mushrooms and tomatoes with oil and sprinkle with salt and pepper. Arrange mushrooms, stemmed sides down, and tomato halves, cut sides up, on a broiler pan. Broil 6 inches from heat, turning over mushrooms halfway through cooking, until tender and tomatoes are slightly charred, about 7 minutes total.
While vegetables are broiling, fill a deep 10-inch skillet with 1 1/4 inches cold water. Add white vinegar and bring to a simmer.
Break 1 egg into a cup, then slide egg into simmering water. Repeat with remaining eggs, spacing them in skillet, and poach at a bare simmer until whites are firm but yolks are still runny, 2 to 3 minutes. Gently transfer eggs with a slotted spoon to paper towels to drain and season with salt and pepper.
Sprinkle stemmed sides of mushrooms with balsamic vinegar, then put 1 tomato half, cut side up, on each mushroom and top with an egg. Grate cheddar cheese on top and sprinkle with chives.