Roasted Red Pepper and Sweet Potato Soup
Peppers and sweet potato roast until they collapse, then get blended with harissa and stock into a soup built around the two nutrients skin research keeps circling back to.
Why it works
Two nutrients carry this whole pot. Beta-carotene from the sweet potato converts to retinol, the vitamin A that regulates keratinocyte turnover and happens to be the parent compound of every retinoid a dermatologist prescribes. Vitamin C from the peppers is the rate-limiting cofactor for the two enzymes that hydroxylate proline and lysine in collagen synthesis, and without it the collagen triple helix falls apart, which is why scurvy shows up as skin and connective tissue failure. Roasting instead of boiling matters here: carotenoids are fat soluble, and heat makes them more available, so the olive oil on the tray is doing real work, not just flavor. This is nutrition, not a topical, and it moves on a timescale of months, not days.
The biochemistry of vitamin C in collagen synthesis and beta-carotene's conversion to retinol is settled science. Whether raising dietary intake above adequacy changes how skin looks is a lot less clear, and the dietary trials are small. Sunscreen and not smoking remain the two interventions with real evidence behind them, and neither one is in this pot.
Ingredients
- 4 red peppers, halved and seeded
- 800 g sweet potato, cut into chunks
- 1 onion, quartered
- 4 garlic cloves, unpeeled
- 3 tbsp extra-virgin olive oil
- 1 tbsp harissa paste
- 1 tsp ground cumin
- 1.2 litres low-sodium vegetable stock
- 1 lemon, juiced
- 150 g plain yoghurt, to serve
- 2 tbsp pumpkin seeds, toasted, to serve
Method
- Heat the oven to 220C. Toss the peppers, sweet potato, onion and unpeeled garlic with the olive oil on a large tray and roast for 35 minutes, until the peppers have blistered and the sweet potato edges have caramelised.
- Squeeze the garlic out of its skins and tip everything into a pot with the harissa, cumin and stock.
- Simmer for ten minutes, then blend until smooth. A stick blender in the pot saves washing a jug.
- Add the lemon juice and taste. Roasted sweet potato is sweet enough that this needs more acid and salt than you expect.
- Cool within two hours and portion. Yoghurt and toasted pumpkin seeds go on at the table.
