Gather all your ingredients and chop the onion finely while measuring out the broth and garlic.
In a skillet over medium heat, warm the olive oil until it shimmers and begins to smell fragrant. Add the chopped onion and minced garlic, sautéing until the onion becomes translucent and soft, about 3-4 minutes. You should hear a gentle sizzle and see the onion turn a light golden.
Pour the sautéed onion and garlic into the slow cooker. Add the crushed tomatoes and vegetable broth, stirring to combine everything evenly.
Cover the slow cooker and set it to low. Let it simmer gently for 6 to 8 hours, during which the tomatoes will break down further, filling your kitchen with a warm, inviting aroma.
Once the cooking time is up, carefully use an immersion blender directly in the crockpot to blend the soup until it’s silky smooth. If you don’t have an immersion blender, transfer the soup in batches to a blender and puree carefully, holding the lid tightly to prevent splashes.
Stir in the cream or coconut milk to add richness and a velvety texture. Taste the soup and adjust with a pinch of salt or a squeeze of lemon juice if needed for brightness.
Chop fresh basil and stir it into the soup just before serving to infuse a bright herbal aroma. Ladle the hot soup into bowls and garnish with extra basil leaves or a drizzle of olive oil for finishing touches.
Enjoy your velvety, smoky tomato soup while it’s warm, preferably with crusty bread or a grilled cheese for a comforting meal.
