Adjust rack to top position (top and middle positions for 4 servings) and preheat oven to 425 degrees. 

In a small pot, combine rice, ¾ cup water (1½ cups for 4), and a pinch of salt. Bring to a boil, then cover and reduce to a low simmer. Cook until rice is tender, 15-18 minutes. 

Keep covered off heat until ready to serve. 

While rice cooks, wash and dry produce. 

Cut broccoli into bite-size pieces if necessary.

Pat pork* dry with paper towels; season all over with half the garlic powder (you'll use the rest in the next step), salt, and pepper. 

Heat a drizzle of oil in a large pan over medium heat. Add pork and sear, turning occasionally, until browned all over, 4-8 minutes (it'll finish cooking in the next step). Transfer pork to one side of a baking sheet. (For 4 servings, spread pork out across entire sheet.)

On opposite side of sheet from pork, toss broccoli with a drizzle of oil, remaining garlic powder, salt, and pepper. (For 4 servings, toss broccoli on a second baking sheet.) 

Roast on top rack until pork is cooked through and broccoli is browned and tender, 12-15 minutes. (For 4, roast broccoli on top rack and pork on middle rack, swapping rack positions halfway through.)

Transfer pork to a cutting board to rest for at least 5 minutes. 

While pork and broccoli roast, in a small bowl, combine chimichurri and sour cream. 

Thinly slice pork crosswise.

Fluff rice with a fork; stir in 1 TBSP butter (2 TBSP for 4 servings) until melted.

Divide rice and broccoli between plates in separate sections. Top rice with pork; spoon creamy chimichurri over pork. Serve.