This "shoulder" season of unpredictable weather — sunny today, drizzly tomorrow — is a great time for vegetable soup.

Here's a simple technique that serves as a canvas for about just about any combination. It's quick and easy and creates a simple meal that's hardy enough to satisfy but won't weigh you down.

The basic recipe makes delicious use of vegetables that are perhaps past their prime. It helps to roast the vegetables first to enhance their character. Roasting draws out moisture and concentrates flavors. Use about 1 tablespoon of oil per pound of vegetables, and be sure to use a flavorful oil such as coconut, olive or ghee. Then lightly spice and salt the vegetables and spread them out on a baking sheet, making sure they don't touch and steam. They'll caramelize and take on a nutty taste in the high, dry heat. Roasted vegetables also make a fine side dish (if you don't nibble them all right from the pan), so make up a double batch.

Every good vegetable soup starts by making a base. Simply sauté a chopped onion or leek in oil or butter before adding a stock of your choice along with the roasted vegetables and a peeled chopped potato for body, then simmer everything together. Pureé the mix to make a smooth, velvety soup without the addition of cream, or purée just half of it if you prefer some texture. Either way, you'll have a simple, luscious meal.

Cauliflower and Romanesco are particularly good choices for a lively spring soup. When roasted, their florets darken and soften and their slightly cabbage-y flavors turn mildly sweet. These vegetables take especially well to warm spices — cumin, coriander, ginger, turmeric — for a soup that takes the chill off spring.

Roast Cauliflower Soup

Serves 4 to 6

Note: Roast an extra batch of cauliflower to enjoy as a side dish or to toss with pasta and then make soup. This soup will keep covered in the refrigerator for up to five days and freezes nicely. Just bring to a boil and season to taste. From Beth Dooley.

• 1 large head cauliflower, about 2 lb.

• 2 tbsp. vegetable or olive oil

• 1 tsp. ground cumin

• 1/2 tsp. ground coriander

• 1/2 tsp. ground ginger

• 1/2 tsp. ground turmeric

• Salt and freshly ground black pepper, to taste

• 2 tbsp. unsalted butter or olive oil

• 2 large leeks, trimmed, white and light green part, chopped

• 2 cloves garlic, minced

• 1 large potato, peeled and cut into chunks

• 4 c. vegetable or chicken stock

• Chopped parsley for garnish, optional

Directions

Preheat oven to 400 degrees. Remove and discard the green leaves of the cauliflower, cut the florets and the stem into 2-inch pieces. In a large bowl, toss the cauliflower with enough of the oil to lightly coat. Then toss with the cumin, coriander, ginger, turmeric and a little salt and pepper. Spread out on a baking sheet so that the pieces do not touch. Roast until the cauliflower is lightly browned and cooked through, about 25 minutes. Set a few roasted florets aside to garnish the soup if you wish.

Heat the butter or oil in a large saucepan or Dutch oven set over low heat. Add the leeks and garlic and sauté until fragrant, about 3 minutes. Stir in the potato and the stock and bring to a simmer and cook until the potato is tender, about 10 minutes. Add the roasted cauliflower and simmer until the flavors come together, about 5 minutes. Purée the soup in batches using a blender or use an immersion blender directly in the pot. Taste and adjust the seasonings. Serve the soup garnished with the reserved florets, if you wish.

Beth Dooley is the author of "In Winter's Kitchen." Find her at bethdooleyskitchen.com.