Chop the onion and prepare the garlic, peeling and keeping whole or crushing depending on your preference.
Pour olive oil into the crockpot and add the diced onion along with the whole garlic cloves. Sauté on high for 10 minutes until the onion becomes translucent and fragrant.
Add the ripe tomatoes to the crockpot, along with a pinch of salt and pepper. Cover with vegetable broth and stir to combine.
Set the crockpot to low and cook uncovered for 6 to 8 hours, allowing the flavors to meld and the tomatoes to soften into a rich, fragrant mixture.
Once the cooking time is up, carefully transfer the hot mixture to a blender using a ladle, then blend until smooth and velvety. Alternatively, use an immersion blender directly in the crockpot.
Pour the pureed soup back into the crockpot if needed, and stir in chopped fresh basil or herbs. Warm for another 10 minutes until heated through and fragrant.
Taste the soup and adjust seasoning with more salt, pepper, or herbs as desired. Serve hot in bowls, garnished with extra basil or a drizzle of olive oil for extra flavor.
