How to Make It
Heat 3 tablespoons of the oil in a large skillet over medium-high heat. Season the scallops with ¼ teaspoon each salt and pepper and cook on one side until just browned, 2 to 3 minutes; transfer to a plate.
Add the fennel, onion, ½ teaspoon salt, and ¼ teaspoon pepper to the skillet and cook, stirring occasionally, until the vegetables are just tender, 5 to 6 minutes. Add the clam juice, wine, and tomatoes and cook until the liquid begins to thicken, 6 to 8 minutes more. Add the scallops, browned-side up, and cook until cooked through, 2 to 3 minutes more.
Meanwhile, rub the baguette slices with the garlic and, dividing evenly, drizzle with the remaining 2 teaspoons of oil. Sprinkle the scallops, vegetables, and cooking liquid with the fennel fronds and serve with the baguette slices.