Warm the olive oil in a large heavy-based saucepan on medium heat.
Once the oil is shimmering, add the chopped onion and carrot and cook, stirring often, until the onion has softened and is turning translucent, about 5 minutes.
Add the garlic, cumin, curry powder, and thyme. Cook until fragrant while stirring constantly, about 2 minutes.
Pour in the diced tomatoes and cook for a few more minutes, stirring often, in order to enhance the flavours.Pour in the lentils, broth, and water. Add 1 teaspoon salt and a pinch of red chili flakes. Season generously with freshly ground black pepper.
Bring the mixture to a boil, then partially cover the pot and reduce the heat to maintain a gentle simmer. Cook for 30 minutes, or until the lentils are tender but still hold their shape. Add more water if needed.
Add the chopped spinach and cook for 5 more minutes, or until the spinach has softened to your liking. Remove the pot from the heat and stir in 1 tablespoon of lemon juice and chutney.
Taste and season with more salt, pepper, or maybe lemon juice.