Preheat oven to 425F. Cover a large baking sheet with parchment paper.
Toss potatoes with 1 tbsp olive oil and 1/4 tsp salt. Carefully spread them on the baking sheet and roast for 20 minutes in the oven.
Meanwhile, combine broccoli, red onion, bell peppers with 1 tbsp olive oil, 1/4 tsp salt, and 1/4 tsp black pepper.
In a small bowl, combine smoked paprika, remaining 1/4 tsp salt, and remaining 1/4 tsp black pepper. Rub Dijon mustard all over the pork tenderloin, then coat with the paprika mixture.
Remove the baking sheet from the oven. Stir the potatoes, then add the broccoli, onion, and peppers to the pan. Drizzle with the remaining 1 tbsp olive oil and toss the vegetables lightly.
Place the pork tenderloin on the baking sheet on top of the vegetables.
Wrap garlic cloves with a little bit of oil in foil and add it on the side of the sheet pan.
Return to the oven and roast for about 25 minutes until the pork reaches 145F in the thickest part. Vegetables should be tender and browned.
Transfer pork to a cutting board and let rest for 5–10 minutes before slicing.
Blend Greek yogurt, baked garlic cloves, lemon juice, and chopped dill in a blender. Season with a little salt and pepper if desired.
Divide sliced pork, potatoes, broccoli, peppers, and onion among 4 plates or 4 food containers. Serve with the Greek yogurt dill sauce.
Store in the fridge for up to 3-4 days in airtight containers.