Preheat oven to 375 degrees Fahrenheit (190 degrees Celsius). Line a baking sheet with parchment paper.

Toss the sourdough in olive oil, salt, and seasonings of choice. Spread out in a single layer on the prepared baking sheet. Bake for 10–15 minutes, tossing halfway through, until the edges are golden and crisp. Let cool slightly.

Preheat oven to 400 degrees Fahrenheit (200 degrees Celsius).

Slice the top off the head of garlic to expose the cloves. Drizzle with one tablespoon olive oil, wrap it in aluminum foil, and roast for 35–40 minutes, until soft and golden. Let cool slightly, then squeeze out the cloves.

Heat two tablespoons olive oil in a large pot. Add onion and sauté for five to six minutes, until soft. Add carrots and tomatoes. Stir in water, chicken consommé, salt, pepper, oregano, and crushed red pepper.

Add the roasted garlic cloves. Stir and let the soup simmer for 45–50 minutes, until the carrots are fork-tender.

Remove from heat and stir in basil. Let it wilt for a few minutes.

Using an immersion blender, blend the soup until completely smooth. Stir in the lemon juice or vinegar.

Taste and adjust seasoning. Ladle into bowls and top with sourdough croutons.

Garnish with extra basil and a drizzle of olive oil or chili oil.