Cheesy Lentil-and-Black-Bean Nachos

Preheat oven to 375°F. In a medium saucepan, cook mushrooms over medium-high heat, stirring occasionally, until liquid evaporates and they're browned in places, 4 to 5 minutes. Add oil, 1 cup onion, garlic, and chopped chile; cook until softened, 5 to 6 minutes.

Add chili powder, 1 3/4 teaspoons salt, and 1/4 teaspoon pepper; cook until fragrant, about 2 minutes more. Stir in lentils, crushed tomatoes, and 3 cups water. Bring to a boil, then reduce heat to low and simmer, partially covered, until lentils are tender and sauce has thickened slightly, 25 to 30 minutes. Stir in beans; cook until warmed through, 1 to 2 minutes. Season with salt and pepper.

Spread half of tortilla chips in an even layer on a rimmed baking sheet. Top evenly with half each of lentil mixture and cheese. Repeat with remaining chips, lentil mixture, and cheese. Bake until cheese melts, 8 to 10 minutes. Top with tomatoes, cilantro, remaining 1/2 cup onion, and sliced chile; serve immediately with a squeeze of lime.