Drizzle olive oil over bread and toast lightly in the oven.
In a large bowl, add tomatoes, lime juice, balsamic and sugar and stir to combine.
In a medium saute pan over medium-high heat, add onion and cooked until caramelized. Add radicchio and mushrooms and cook until radicchio has wilted and mushrooms have released their liquid. Season, to taste, with salt and pepper. Add minced garlic and cooked bacon and stir to combine. Remove from heat and allow to completely cool.
Fold cooked onion-bacon mixture into the tomato mixture and add the chopped cilantro.
Preheat grill to high.
Grill shrimp and scallops until opaque. Season both sides with salt, pepper and crushed red pepper flakes. Remove from the grill and slice the scallops and shrimp in half.
Top each toasted bread slice with the tomato mixture, grilled scallop, and grilled shrimp and garnish with sliced green onions.