Set a 6-quart stockpot with 1 gallon of water over high heat and bring to a boil. Add the onions, carrots, celery, garlic, bay leaves, vinegar, lemons and juice, salt and cayenne pepper. Bring the pot to a boil and allow to cook for 15 to 20 minutes. Place the lobster into the water and cook until red and cooked through, about 7 to 8 minutes. Immediately immerse in ice water to halt the cooking. Once the lobsters have cooled, remove from the water and set aside.
Use a chef's knife to crack the shell of the lobsters and remove the tail meat and claw meat. Chop the lobster into 1/2-inch pieces, and set aside. Place a sixth of the greens into each of 6 large chilled martini glasses. Drizzle a little of the dressing over the greens. Place 1/4 cup of the tomatoes in each of the glasses, as well as 1/4 cup of the hearts of palm, 1/4 cup orange segments and a sixth of the chopped lobster. Drizzle more of the dressing over the parfait and garnish with fresh cilantro sprigs. Serve immediately.