Add half the orzo (use all for 4 ppl) to the boiling water. Cook uncovered, stirring occasionally, until tender, 10-12 min. Drain and rinse with cold water until cool to the touch. Return orzo to the same pot, off heat. Stir in 1 tsp (2 tsp) oil.
Meanwhile, zest, then juice half the lemon (whole lemon for 4 ppl). Cut any remaining lemon into wedges. Peel, then mince or grate garlic. Core, then cut pepper into ¼-inch pieces. Cut tomato into ¼-inch pieces. Drain, then cut or tear olives in half.
Meanwhile, pat pork dry with paper towels. Add pork, Dill-Garlic Spice Blend, half the garlic and 2 tsp (4 tsp) oil to a medium bowl. Season with salt and pepper, then toss to coat. Arrange pork on a parchment-lined baking sheet. Roast in the bottom of the oven until golden-brown and cooked through, 14-16 min.** Transfer pork to a clean cutting board to rest, 2-3 min.
Meanwhile, add lemon zest, sour cream, remaining garlic and 1 tbsp (2 tbsp) water to a small bowl. Season with salt and pepper, then stir to combine.
Combine lemon juice, ½ tsp (1 tsp) sugar and 1 tbsp (2 tbsp) oil in a large bowl. Add orzo, spring mix, tomatoes, peppers, feta and olives. Season with salt and pepper, then toss to combine.
Thinly slice pork. Divide salad between plates. Arrange pork over top. Dollop with creamy lemon dressing. Squeeze a lemon wedge over top, if desired.