- 2 pounds ripe but firm tomatoes (about 5 medium)
- 1 cup day-old country-style bread such as Sam's Tomato Sourdough, diced into 1/4-inch cubes
- 1 teaspoon fennel seeds
- 1 medium clove garlic, minced
- 1 medium bunch green onions, roughly chopped, including tender green stems (about 3/4 cup)
- 3/4 teaspoon Worcestershire sauce
- 1 tablespoon fresh lemon juice
- 2 tablespoons extra-virgin olive oil, more for drizzling
- 1/4 teaspoon freshly ground black pepper
- 4 cups baby arugula, loosely packed (about 1 large bunch), tough stems removed and torn into 1-inch pieces
- 2 ounces well-chilled goat cheese, crumbled
- Kosher salt
- Preheat the oven to 400°F. Slice the tomatoes in half, length- or width-wise, to make little tomato “boats.” Roma-style varieties tend to work well length-wise; beefsteaks width-wise, but it varies depending on the size and shape. If your tomatoes are too narrow to slice in half, slice the top third off of each. Scoop out the insides with a spoon and smash the flesh over a colander-lined bowl. Place the tomato halves upside down on paper towels to drain.
- Place the cubed bread on a baking sheet and bake until lightly toasted, 5 to 6 minutes, stirring occasionally. Set aside to cool.
- Heat a small saucepan over medium-high heat and toast the fennel seeds, shaking the pan occasionally, until the seeds just begin to brown, about 2 minutes (they will not darken significantly). Coarsely grind the seeds in a mortar and pestle with a generous pinch of salt. Add the garlic, 1 tablespoon chopped green onions, and Worcestershire sauce and continue to grind until you have a rough paste. Stir in the lemon juice, olive oil, and pepper. Set the dressing aside.
- Lightly drizzle a 9- or 10-inch baking dish with olive oil. Snugly arrange the tomatoes side-by-side, cut side up, in the dish. Sprinkle the tomatoes lightly with salt and bake until the flesh just begins to soften, 5 to 6 minutes for juicy varieties such as beef steaks, and 7 to 9 minutes for firmer varieties such as paste tomatoes. Remove the tomatoes from the oven and reduce the temperature to 350°F.
- Meanwhile, combine the arugula, remaining green onions, 1/2 cup drained tomato flesh (reserve the tomato water for another use), toasted croutons, and lemon-fennel dressing in a medium bowl. Mix well and fold in all but 2 tablespoons of the goat cheese. As soon as you remove the tomatoes from the oven, divide the mixture evenly between them, packing each tomato tightly with filling. Sprinkle the remaining goat cheese on top. Bake until tomatoes are tender (but still hold their shape when pierced with a sharp knife) and the arugula has wilted slightly, 5 to 10 minutes, depending on the size and variety of tomato. Drizzle with olive oil, season with salt and pepper to taste, and serve immediately.