Low-Carb Roasted Ratatouille Soup with Basil Mayonnaise

I'm excited to share my new recipe with you: I think you're going to love it.  It tastes glorious and sunny, like summer in a bowl, and is easy to make (although like all good food it does take time to make). The only part of this recipe that's remotely tricky is the home-made basil mayonnaise, but you can omit this topping if you don't feel confident about making mayo, and the soup will still taste very good without it. Do give the mayonnaise a try, though: it's not anywhere as difficult to make as TV chefs will have you believe.

Low-Carb Roast Ratatouille Soup with Basil Mayonnaise

I'm a devoted fan of ratatouille. Not the watery, chuck-everything-in-a-saucepan-and-stew-to-a-mush variety, but a beautiful meeting of ripe tomatoes, shiny eggplants, snappy courgettes, onions and red peppers, slowly roasted with olive oil and garlic to a silken, jewel-bright deliciousness (try my oven-roasted ratatouille recipe).

As always, the quality of the raw ingredients determines how good the soup will taste. Ripe, plump, vividly coloured vegetables will produce a soup of unrivalled quality, and it is always better the next day, once the flavours have had a chance to mingle and mature.

This recipe serves 6, but is easily doubled. It's low in carbs, excellent if you're on a #LCHF regime, and very suitable for diabetics.





Roasted Ratatouille Soup with Basil Mayonnaise

5 large, ripe tomatoes
2 plump brinjals [aubergines/eggplants], or four smaller ones
2 large, deep-red peppers [capsicums]
8 courgettes [zucchini]
2 large white onions, peeled
½ cup (125 ml) extra-virgin olive oil
flaky sea salt
freshly milled black pepper
6 fat cloves garlic, unpeeled
5 cups (1.25 l) water, plus more for thinning

For the basil mayonnaise:

2 large free-range egg yolks, at room temperature
salt
200 ml vegetable oil (such as sunflower or canola oil)
100 ml extra-virgin olive oil
1 cup (250 ml, loosely packed) fresh basil leaves
1 tsp (5 ml) flaky sea salt
the juice of a large lemon
freshly milled black pepper

Heat the oven to 210 ºC.  Using a sharp knife, top and tail the tomatoes, eggplants, red peppers, courgettes and onions, and cut them into small chunks. Pile all the vegetables into a large roasting pan. Drizzle the olive oil over the vegetables, season generously with salt and pepper and, using your hands, toss well to coat.  Tuck the six unpeeled garlic cloves deep into the vegetable bed (but remember where you've hidden them).

Place the  pan, uncovered, in an oven heated to 210 ºC, and roast for 25-35 minutes, or until the vegetables are beginning to turn golden brown in patches.

Now cover the pan with foil, turn the heat down to 180 ºC, and bake for a further 20-30 minutes, or until the veggies are soft.  Remove the roasting tray from the oven. Fish the whole garlic cloves out of the pan, and set aside.

Pour the water (1.5 l) into the pan, replace the foil, and bake at the same temperature for another 15 minutes.  Remove the pan from the oven and set aside for 15 minutes to cool.

A very thick, pale-yellow mayo

While the vegetables are cooling, make the basil mayonnaise. Put the two egg yolks into a small bowl and add the salt.

Mix the vegetable oil and olive oil in a small jug. Place a damp cloth underneath the bowl so that it doesn't skid around while you're making the mayo.

Using a rotary beater or whisk, beat the egg yolks and salt for a minute. If you don't have such a gadget, use an ordinary wire whisk, and plenty of elbow power. Now, as you whisk the egg yolks with one hand, pick up the jug of oil with the other, and dribble a little splash of oil onto the yolks.  Keep whisking and dribbling, a little splash at a time, with great energy, and within a few minutes you will see the egg mixture begin to thicken rather dramatically.

Keep adding the oil, a dribble at a time, until you have a thick yellow ointment. You may not need to add all the oil: stop adding oil once the mayonnaise has thickened to your liking. (If your mayonnaise doesn't thicken, or it curdles, click here.)  Set the mayonnaise aside.

Roughly chop the basil leaves, and place in a mortar along with the salt. Pound to a rough paste.  (If you don't have a mortar, put the leaves and salt onto a wooden chopping board, and smash them with a rolling pin). Scrape the pounded basil into a little bowl.  Take three of the roast garlic cloves you have set aside and squeeze the soft, baked pulp into the basil mixture. Add the fresh lemon juice and stir well.  Now stir this mixture into the mayonnaise, season to taste with salt and pepper, tip into a clean bowl, and refrigerate.

Tip the contents of the roasting pan into a big bowl, and blitz with a stick blender, or use a food processor or liquidiser to process to a slightly coarse purée.  If the soup mixture seems too thick, or the blades refuse to turn, thin it down with a little boiling water.  Squeeze the pulp of the remaining three cloves of baked garlic into the mixture, season with salt and pepper to taste, and blitz for another minute.

Return the soup to the stove-top and reheat.  Serve your soup piping hot, topped with a dollop of cold basil mayonnaise.

Serves 6. 

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