In a large stockpot over medium heat, combine the crab boil, water and lemons. Bring to a boil. Add the lobsters and cook for 4 minutes. Remove from the heat and cool. Preheat the grill. Split each lobster in half. Season the lobster meat with 3 tablespoons of the olive oil, salt and pepper. Place each lobster, meat side down and grill for 3 to 4 minutes on each side, turning the lobsters every 2 minutes. In a large saute pan, over medium heat, add the remaining olive oil. When the oil is hot, add the beans. Season with salt and pepper. Saute for 2 minutes. Add the shallots and tomatoes. Season with salt and pepper. Continue to saute for 3 to 4 minutes or until the tomatoes start to break their skin. Remove from the heat. To serve, mound the potatoes in the center of each plate. Spoon the bean/tomato mixture around the potatoes. Lay the grilled lobster on top of the potatoes. Drizzle the entire plate with the truffle oil. Garnish with chives.