3 tablespoons olive oil, divided
1/2 medium onion, finely chopped
1/4 teaspoon salt, plus more for seasoning
Freshly ground black pepper
1 cup dried green, brown, or French lentils
1 cup chicken or vegetable broth
1 cup water
1/2 cup roasted red peppers, jarred or homemade
1/2 cup bulgur
1 tablespoon sherry vinegar, plus more as needed
1 pound uncooked large (17 to 21 count) shrimp, peeled and deveined
1/4 cup finely chopped fresh Italian parsley
Arrange a rack in the middle of the oven and heat it to 400°F.
Meanwhile, heat 2 tablespoons of the oil in a medium saucepan over medium heat. Add the onion and 1/4 teaspoon salt, season with pepper, and cook, stirring occasionally, until the onion is tender, about 8 minutes.
Add the lentils and stir to coat in the onion and oil. Add the broth and water and bring to a boil, and then reduce the heat to low and simmer uncovered until the lentils are just tender, 20 to 30 minutes. Meanwhile, cut the red peppers into small dice.
When the lentils are ready, remove from the heat and stir in the peppers and bulgur. Cover and set aside until the bulgur is tender, about 10 minutes. Meanwhile, roast the shrimp.
Place the shrimp on a baking sheet, drizzle with the remaining 1 tablespoon oil, season with salt and pepper, and toss with your hands to coat. Spread into a single layer and roast until just opaque and cooked through, 6 to 8 minutes.
Drain off any excess liquid from the bulgur and lentils. Stir in the sherry vinegar and parsley; taste; and season with salt, pepper, and more vinegar as needed. Transfer to serving bowls and top with the roasted shrimp.