Dill-Crusted Pork Tenderloin with Farro Salad

2 garlic cloves, finely chopped
5 tablespoons coarsely chopped dill, divided
2 tablespoons finely grated lemon zest, divided
3 tablespoons fresh lemon juice, divided
6 tablespoons olive oil, divided
2 1/2 teaspoons kosher salt, divided
1/2 teaspoon freshly ground black pepper
1 (1 1/2-pound) pork tenderloin
1 pint cherry tomatoes
3 cups (loosely packed) arugula (about 3 ounces)
2 cups cooked whole farro
3/4 cup frozen peas, thawed (about 4 ounces)
1/2 cup (loosely packed) crumbled feta (about 2 ounces)
Flaky sea salt (optional)

Preheat oven to 425°F.
Mix garlic, 2 Tbsp. dill, 1 Tbsp. lemon zest, 1 Tbsp. lemon juice, 1 Tbsp. oil, 1 1/2 tsp. kosher salt, and pepper in a small bowl with a fork to create a paste.
Pat pork tenderloin dry and rub with paste.
Heat 1 Tbsp. oil in a large oven proof skillet over medium-high.
Sear pork, turning occasionally, until golden brown on all sides, 10–12 minutes.
Add tomatoes, then transfer to oven and roast until an instant-read thermometer inserted into the thickest part of pork registers 145°F and tomatoes are lightly blistered and softened, about 10 minutes.
Transfer pork to a cutting board and let rest at least 5 minutes before slicing.
Meanwhile, whisk remaining 1/4 cup olive oil, 2 Tbsp. lemon juice, and 1 tsp. kosher salt in a medium bowl.
Add arugula, farro, peas, feta, and remaining 3 Tbsp. dill and 1 Tbsp. lemon zest; toss well to combine.
Gently fold in roasted tomatoes.
Slice pork and transfer to a platter; season with sea salt, if using.
Serve with farro salad alongside.