Preheat your grill or oven broiler. Char the poblano peppers until their skins are blistered and blackened. Place them in a bowl and cover with plastic wrap to steam for about 10 minutes. After steaming, peel off the charred skin, remove the seeds, and chop the peppers.

Preheat your oven to 400°F (200°C). Rub the beef tenderloin with 2 tablespoons of olive oil, garlic powder, onion powder, and salt. Press the crushed black peppercorns onto the surface to create a crust.

In a large oven-safe skillet, heat 1 tablespoon of olive oil over medium-high heat. Sear the beef tenderloin on all sides until browned, about 3-4 minutes per side. Transfer the skillet to the preheated oven and roast for 20-25 minutes until the internal temperature reaches your desired doneness (135°F for medium-rare).

Toss the diced eggplant and chopped onion with the remaining 1 tablespoon of olive oil, salt, and smoked paprika. Spread them out on a baking sheet and roast in the oven for the last 20 minutes of the tenderloin's cooking time until soft and slightly caramelized.

In a medium saucepan, heat a splash of olive oil over medium heat. Add the minced garlic and sauté until fragrant. Add the roasted eggplant and onion mixture, then pour in the vegetable broth. Bring to a simmer and cook for about 10 minutes. Use an immersion blender to puree the mixture until smooth. Stir in the balsamic vinegar and adjust seasoning if necessary.

Once the tenderloin is done, let it rest for about 10 minutes before slicing. Serve the sliced tenderloin over a generous spoonful of the velvety roasted eggplant gravy and garnish with chopped fresh parsley.