1. Preheat oven to 450F.
2. Cut the eggplant and potatoes into 1 inch thick rounds. Cut the 1/2 inch thick rounds.
3. Place eggplant, zucchini, and potatoes on separate baking sheets. Drizzle each tray with about two tablespoons olive oil, sprinkle with sea salt, and toss to coat.
4. Spread vegetables in an even layer, and roast until they're golden and tender, flipping vegetables when the bottoms have caramelized.
5. The zucchini will take about 20 minutes, the potatoes and eggplant 30-40 minutes.
6. Meanwhile, place bell peppers over an open, medium flame and roast, turning frequently with a pair of tongs, until the skin is blackened and blistered all over.
7. Let peppers cool. Peel away and discard the skin, stem and seeds. Slice peppers lengthwise into quarters, then cut the quarters crosswise into quarter inch thick slices.
8. In a dry skillet, toast the cumin seeds over a medium flame until fragrant, 30-60 seconds. Let cool, then grind in a mortar and pestle or spice grinder.
9. Peel onions, halve them, then slice them thinly. Peel and chop garlic finely.
10. Heat remaining half of olive oil in a large soup pot or dutch oven over medium heat.
11. Add onions, ground cumin, sweet and smoked paprika, turmeric, ginger, cinnamon stick, saffron, and salt. Cook, stirring frequently, until onions are tender, 5 minutes.
12. Add garlic, lower the heat a bit, and continue cooking until the onions are very tender, 5-10 minutes more.
13. Coarsely chop the tomatoes and add them to the pot (with their juices).
14. Add chickpeas to the pot of onions along with 4 cups of water (per 4 servings). Add the roasted vegetables.
15. Bring the tagine to a bare simmer, and cook gently, stirring once or twice, until the tomatoes are beginning to break down,10-15 minutes.
16. When the tagine is done, remove the pot from the heat.
17. Coarsely chop the parsley and juice half the lemons. Then stir the parsley and lemon juice into the tagine. Add more lemon or salt to your taste. Serve the tagine warm.