Preheat the oven to 350°F. Peel and finely slice the garlic, then place it in a large casserole pan on a medium-high heat with 2 tbsp of olive oil and the mixed veg. Fry for a few minutes while you slice 1 lb of the mushrooms, then add them to the pan with a good pinch of black pepper. Cook for 10 minutes, or until golden, then pour in the stock and cook for a further 10 minutes. Meanwhile, slice the remaining ½ lb of mushrooms (slice them so you have some beautiful cross-sections, throwing any trimmings into the soup as you go), place on a baking sheet with a drizzle of olive oil and a pinch of sea salt and pepper, and roast for 15 minutes, or until beautifully golden and crisp.