Adapted from Eating Well

Ingredients 
4 tsp. extra-virgin olive oil, divided
1 1/2 tsp. ground coriander
1 tsp. kosher salt, divided
1/4 tsp. freshly ground pepper
1-1 1/4 pounds pork tenderloin, trimmed
1 large sweet onion, sliced
2-4 Tbsp. water
2 c. diced rhubarb
1/4 c. red-wine vinegar
1/4 c. brown sugar
1/4 c. minced fresh chives

Instructions
Preheat oven to 450°F.

Rub 1 tsp. oil, coriander and 1/2 tsp. of salt and pepper into pork.

Heat 1 tsp. oil in a large ovenproof skillet over medium-high heat. Place pork in pan and cook, turning occasionally, until brown all over (5-7 mins). Transfer skillet to oven and roast pork until interior of meat reaches 145°F (15-17 mins) Remove from oven and let rest.

While the pork is in the oven, heat 2 tsp. oil in a skillet over medium heat. Toss in onion and 1/2 tsp of salt. Saute onions until brown. Add 2 Tbsp. water and cook for 5-7 mins more until onion is soft. Add water as necessary to prevent burning. Stir rhubarb, vinegar and brown sugar into cooking onions and continue to stir until rhubarb has broken down (about 5 mins). Spoon sauce over sliced pork and serve with a garnish of chives.