Start by preparing your ingredients: halve or quarter the ripe tomatoes, mince the garlic, and dice the onion. Heat a skillet over medium heat and add a tablespoon of olive oil, letting it warm until fragrant.
Add the garlic and onion to the skillet, sautéing until they become fragrant and just golden, about 3-4 minutes. The aroma should be warm and inviting, and the onions will soften slightly.
Stir in the prepared tomatoes, cooking for an additional 5 minutes until they soften and release their juices, filling the skillet with a rich, roasted aroma.
Transfer the tomato mixture into your slow cooker, pouring in the vegetable broth and stirring well. Add a pinch of salt and pepper to season generously.
Set the slow cooker to low and cook for 6-8 hours, allowing the flavors to meld and deepen. The house will fill with a warm, roasted tomato scent as it simmers.
Once the cooking time is up, carefully transfer the hot soup to a blender or use an immersion blender directly in the crockpot. Blend until the soup is smooth, silky, and velvety—no chunks remaining.
Taste the soup and adjust the seasoning with more salt and pepper if needed. Stir in chopped fresh basil for a vibrant herbal note, or add dried basil earlier during cooking for a subtler flavor.
Pour the finished soup into bowls, garnish with extra basil leaves if desired, and finish with a drizzle of good-quality olive oil for an added layer of richness. Serve hot with crusty bread or your favorite side.
