Finely dice the onion and mince the garlic. Peel, core, and cube the quinces. Slice the carrot and peel/cube the pumpkin into similar-sized pieces.
Heat olive oil in a large pot over medium heat. Add onion; cook ~5 minutes until softened and lightly golden. Add garlic; cook 1 minute until fragrant.
Add cumin, coriander, cinnamon, and chilli flakes. Stir for 30 seconds to wake up the flavours.
Tip in quince, pumpkin, and carrot. Stir to coat in the spiced oil; cook 3–4 minutes to start softening.
Add tomatoes, chickpeas, lentils, and stock. Season with salt and pepper. Pour in the saffron + its soaking water and stir.
Cover and cook on low for 50–60 minutes, stirring occasionally, until lentils are tender and quince is soft. Add a splash of water if it thickens too much.
Once cooked, stir vigorously for a creamier stew (lentils/quince will break down), or keep it chunky.
Stir in honey. Taste and adjust salt, pepper, and lemon juice. Ladle into bowls, top with herbs and yogurt, and serve with couscous, rice, or warm flatbread.