Roasted Cauliflower, Onion, and Potato Soup

Winter just refuses to leave us alone this year. Although the temperatures rose this week, snow and ice remain on the ground. For me, cold weather is soup weather and this Roasted Cauliflower, Onion, and Potato Soup is definitely the ticket. The aroma and the flavor of roasted vegetables are much more complex and intense (in a good way) than when they are prepared any other way. Blended with a light vegetable broth, the vegetables in this soup provide a creamy consistency with no dairy. To borrow a phrase from the wine lexicon, this soup is “mineral.” 

It reminds me of a simple, non-dairy version of vichyssoise (potato and leek soup, traditionally served cold, but also delicious hot.) Roasting the vegetables requires little effort and almost no tending. Using boxed or canned vegetable broth makes this soup a snap to prepare for a weeknight dinner and because it doesn’t have dairy, it will freeze well. 

If you don’t like cauliflower, then I’m betting you haven’t had it roasted. You can even roast a whole head of cauliflower, uncut, for a magnificent presentation. I’ve cut it into smaller pieces, called florets, for faster cooking in this recipe. The side of the cut floret facing down on the pan will brown more quickly than the top, so turning the florets over helps to roast them evenly.

The same roasting tips apply as I mentioned in my recent roasted green bean post – high heat and fat (oil in this case) are essential, the pan should hold the vegetables comfortably and items begin roasted should not touch each other as they cook.

Roasted Cauliflower and Onion Soup

Serves 4-6 (about 6 cups)  Cost – $10

Ingredients

• 1 head of cauliflower, cut into florets
• 2 medium onions, cut into chunks – about 12 ounces
• 2 medium potatoes (I used red), cut into chunks – about 10-12 ounces
• 5 tablespoons (¼ cup + 1 tablespoon) olive oil
• 4 cups vegetable broth ( 1 – 32 ounce box) If you have leftover vegetable broth, use this tip to freeze it for later use. 
• 1 cup or more of water
• 1 teaspoon salt
• Freshly ground pepper
• ¼ – ½ teaspoon soy sauce
• Hot sauce (optional)

Equipment

• Cutting board
• Knife
• Half-sheet size cookie sheet with rim
• Medium size pot
• Blender (I used an immersion blender)
• Measuring cup
• Measuring spoons
• Bowl
• Tongs or fork (for turning roasting vegetables)
• Spatula
• Spoon

Preparation

• Pre-heat the oven to 450 degrees F.
• Cut the cauliflower florets and onion chunks. No need to obsess, but keep the pieces close to the same size so they roast evenly.
• Drizzle 2 tablespoons of the oil on the cookie sheet, add the cauliflower florets and onion chunks and roll them around to coat them, then drizzle 2 more tablespoons of oil over them.

• Put the pan on the center shelf of the oven and roast the vegetables for 30 minutes.
• Toward the end of the 30-minute cooking time, peel and chop the potatoes into chunks and put them in bowl with 1 tablespoon of oil, mixing them until they are coated. (If you cut the potatoes more than a few minutes before they will be cooked, submerge them in a bowl of cool water so they don’t discolor. Then just before the 30 minutes are up, dry the chunks with a clean dishcloth or paper towel before coating them with the oil.)
• Remove the onions from the roasting pan (to a bowl) and turn the cauliflower florets over. Then add the potatoes.

• Cook the cauliflower and potatoes for another 15-20 minutes, turning the potatoes about halfway through that time. Remove the pan from the oven and let the cauliflower and potatoes cool down a bit.  

• Blend all the vegetables in batches with the vegetable broth. If using an immersion blender, the batches have to be smaller than with a regular blender, but in either event, make sure to have enough liquid in each batch so you don’t burn out the motor. As you finish a batch, add it to the pot. When you have finished blending all the vegetables and broth, heat the mixture on a stovetop, adding the salt, pepper, and soy sauce.
• Taste to adjust seasonings. Note that the quality and ingredients of your vegetable broth make a difference in how the soup tastes. Also, if your broth is particularly salty or low in sodium, you may want to adjust the amount of extra salt you add.  Then slowly add the water until you get the consistency you prefer. I like this soup “creamy” and 1 cup of water got it to that consistency: if you prefer thinner soup, just add a bit more water.

Serve with hot sauce.