Ingredients

1 tablespoon olive oil, plus more for serving

1 medium onion, finely chopped (1 cup)

1 tablespoon tomato paste

1 teaspoon dried oregano

1 teaspoon dried thyme

1 cup lentils, picked over and rinsed

1 can (14.5 ounces) diced tomatoes, in juice

2 bunches (about 1 1/2 pounds total) Swiss chard, stalks cut crosswise into 1-inch pieces, leaves torn into 2-inch pieces (keep stalks and leaves separate)

Coarse salt and ground pepper

Juice of 1/2 lemon

Bread, for serving (optional)

Preparation

In a large saucepan with a lid, heat oil over medium-high. Add onion and cook, stirring, until softened and browned, 3 to 5 minutes. Add tomato paste, oregano, and thyme; stir to combine.

Add lentils, 5 cups water, and tomatoes with their juice; bring to a boil. Reduce heat and simmer, partially covered, 20 minutes. Add chard stalks and cook until beginning to soften, about 5 minutes. Add chard leaves; season with salt and pepper, and cook until lentils and chard are tender, 15 to 20 minutes.

Stir in lemon juice; ladle soup into bowls. Drizzle with olive oil, and serve with bread, if desired.