Why This Recipe Works

Ground fennel adheres well to the pork and imparts more flavor than whole fennel seeds.

Before You Begin

You can substitute vine-ripened or heirloom tomatoes for the plum tomatoes.

Instructions

Combine fennel, 1 teaspoon salt, and 1 teaspoon pepper in bowl. Pat pork dry with paper towels and sprinkle with fennel mixture. Grill pork over hot fire, turning occasionally, until well browned and registering 140 degrees, 12 to 15 minutes. Transfer to carving board, tent with foil, and let rest for 5 minutes.

Meanwhile, brush onion with 1 tablespoon oil and sprinkle with remaining ¼ teaspoon salt and remaining ¼ teaspoon pepper. Grill onion over hot fire until lightly charred, about 2 minutes per side; transfer to large bowl. Add tomatoes, basil, capers, vinegar, and remaining 2 tablespoons oil to bowl with onion and toss to combine. Season with salt and pepper to taste. Slice pork and serve with salad.