Peel, trim, and cut carrot into ¼" dice. Bring a small pot with carrots covered with water to a boil over high heat. Boil until tender, 15-18 minutes. While carrots cook, trim ends off green beans. Mince garlic. Peel and halve shallot. Slice thinly. Stem and mince cilantro. Place a medium non-stick pan over medium heat. Add pepitas to hot pan. Stir occasionally until toasted, 2-3 minutes. Remove to a cutting board, then coarsely chop. Wipe pan clean and reserve.
Prepare Beans and Make Sauce
Place green beans and shallots on prepared baking sheet. Toss with 1 tsp. olive oil, ¼ tsp. salt, and a pinch of pepper and spread into a single layer on one side of baking sheet. In a mixing bowl, combine pepitas, cilantro, honey, Sriracha (to taste), and 1 tsp. olive oil.
Sear the Pork Tenderloin
Pat pork tenderloin dry, and season with ¼ tsp. salt and ¼ tsp. pepper. Return pan used to toast pepitas to medium-high heat and add 1 tsp. olive oil. Add pork tenderloin to hot pan and sear on two sides until browned, 3-4 minutes.
Roast Beans and Pork Tenderloin
Transfer pork tenderloin to empty space on baking sheet. Roast until green beans are tender and pork reaches a minimum internal temperature of 145 degrees, 8-10 minutes. Reserve ¼ cup carrot cooking water and drain carrots in a colander.
Finish the Dish
Wipe pot used to cook carrots out and add butter and garlic. Return to medium heat and cook until butter is melted and garlic aromatic, 30-60 minutes. Remove from burner and return carrots. Mash until desired consistency is reached, adding reserved carrot water 1 Tbsp. at a time if needed. Season to taste with salt and pepper. Slice pork tenderloin and shingle on a plate. Top pork slices with sauce. Place green beans next to pork and carrot mash next to beans.