For the Lemon Poppy Seed Dressing: Place all the ingredients in a pint jar and screw the lid on tight. Shake vigorously until smooth. Refrigerate until ready to use.
Preheat the grill. Cut the romaine head in half length-wise. Then quickly grill on both sides until char marks form. Remove and roughly chop the romaine.
Cut the avocados in half and use a large spoon to scoop out the flesh in one whole piece. Cut in half lengthwise, then use a small heart cookie cutter to cut out hearts.
Divide the romaine between 4 plates. Top with pecans, pomegranate arils, and avocado hearts. Drizzle with Lemon Poppy Seed Dressing.