Whisk the lemon juice, vinegar, shallot, olive oil, rosemary, 1/4 teaspoon salt, and pepper to taste in a large bowl. Transfer 3 tablespoons of the dressing to a medium bowl and add the pork, turning to coat; let marinate 15 minutes at room temperature. Add the tomatoes and radishes to the bowl with the remaining dressing.
Preheat a grill or grill pan to high and brush lightly with vegetable oil. Grill the pork until marked, about 2 minutes per side; remove to a plate. Grill the bread, turning once, until warm, about 1 minute.
Add the salad greens to the bowl with the tomatoes and radishes; season with salt and pepper and toss. Divide the salad among plates; top with the gruyere and pork. Drizzle with olive oil and serve with the grilled bread.
Photograph by Justin Walker
Courtesy of Food Network Magazine