Chop the onion, carrots, and celery into small, uniform pieces using your chopping knife. This helps everything cook evenly and meld flavors better.
In a large skillet over medium heat, warm the olive oil until it shimmers and smells fragrant. Add the chopped onion and sauté until translucent, about 5 minutes, until it becomes soft and slightly golden.
Transfer the sautéed aromatics to the crockpot. Add the diced carrots, celery, canned tomatoes with juices, rinsed beans, dried herbs, and pour in the vegetable broth. Stir everything together with a wooden spoon or ladle to combine.
Set the crockpot to low and cover. Let it simmer gently for 6-8 hours; you'll notice the house filling with a savory, smoky aroma as the vegetables soften and flavors meld.
About 20 minutes before serving, add the uncooked pasta to the crockpot. Stir well to submerge the pasta in the broth, then cover and cook on high. The pasta should become tender and soak up the flavors, about 15-20 minutes.
Check the soup and stir to prevent sticking. Taste and season with salt and pepper as needed. If the soup is too thick, stir in a splash of hot water or broth to loosen it up.
Once the pasta is tender and the flavors are well combined, turn off the crockpot. Let it rest uncovered for 5-10 minutes; this helps the broth settle and intensify.
Serve the minestrone hot, garnished with freshly chopped basil or herbs for a burst of brightness. Drizzle with a little olive oil if desired and enjoy this warm, chunky, comforting soup.
