Serve with grilled shrimp, fish, or pork.
Preheat oven to 400 degrees. Coat a baking sheet with cooking spray. Slice tomatoes in half lengthwise; arrange them, cut side down, in a single layer on prepared baking sheet. Place garlic cloves on baking sheet next to tomatoes. Roast in oven until tomatoes are soft and wrinkled, and garlic is aromatic and tender, about 35 minutes. Remove from oven, and let cool.
In a medium bowl, combine fennel with vinegar, capers, red-pepper flakes, and oil. Stir to combine. Finely chop garlic, and roughly chop tomatoes; add to bowl. Slice basil into fine strips; add to bowl along with parsley. Stir to combine; serve chilled or at room temperature.