Chop all the vegetables, garlic, and kale before you start cooking.
Heat the olive oil in a large Dutch oven or heavy soup pot over medium heat. Add the onion, carrots, celery, and 1 teaspoon salt. Cook for 6 to 8 minutes, stirring a few times, until softened.
Add the garlic, black pepper, chili flakes, and Italian mixed herbs and stir for about 1 minute until fragrant.
Add the crushed tomatoes and cook for 2 to 3 minutes, stirring.
Add the roasted red pepper strips, chopped kale, and most of the beans. Reserve about ⅓ of the beans for later.
Pour in the vegetable stock and the 3 cups of water, scraping the bottom of the pot. Bring to a boil.
Reduce to a steady simmer, cover partially, and cook for 10 minutes until the kale is tender.
Stir in the elbow macaroni and simmer uncovered for the time given on the pasta package, usually 8 to 10 minutes, stirring often so the pasta does not stick.
Meanwhile, ladle about 1 cup of hot broth into a jug, add the reserved beans, and blend until smooth, venting the lid if using a regular blender.
Stir the bean puree back into the pot and simmer 1 to 2 minutes until the soup thickens. Add a splash of water if it is too thick and taste the pasta; it should be tender with a slight bite.
Remove from the heat and stir in the lemon juice and most of the parsley. Taste for salt and pepper.
Let the soup stand for 5 minutes, then serve topped with the remaining parsley.