In a large Dutch oven or other heavy pot, heat 1 tbsp. EVOO over medium-high. Season the lamb with salt and pepper and cook, stirring occasionally, until browned, 8 minutes. Using a slotted spoon, transfer to a plate.
Reduce heat to medium. Cook the onion and ginger in 1 tbsp. EVOO, stirring often, until lightly browned, 8 to 10 minutes. Stir in the lamb, 1 1/2 cups stock, honey, chili-garlic sauce and lemon zest; bring to a boil. Reduce heat to medium-low, cover and simmer 1 hour. Stir in the squash and cook until tender, about 30 minutes; season.
Meanwhile, in a medium saucepan, boil the remaining stock. Off heat, stir in the couscous; cover and let sit 5 minutes. Uncover, fluff with a fork, then stir in the lemon juice and remaining 1 tbsp. EVOO; season. Divide the couscous among plates, top with the tagine and mint.