Martha Stewart's trick for thicker, heartier tomato soup is to prepare a roux before adding the tomatoes, which thickens the soup without making it heavy.
Either make the roux in a separate pot and add it to your tomato soup as you would with cream or create it with some onions and garlic before adding any of the other ingredients.
When the minestrone is done, add a few spoonfuls of pesto. For best results, avoid stirring it in completely and instead leave a few swirls here and there.
Martha Stewart reminds us that in French onion soup, it's important to caramelize those onions, so they take on additional sweetness and more depth of flavor.
Getting this trick right takes time and patience. Caramelizing onions could take up to an hour, and you'll need to watch over them as they cook so they don't burn.
Leeks and shallots tend to be milder than onions, providing that signature oniony bite without the spiciness. Just be sure to saute and soften them early in the cooking process.
Stewart suggests putting your vegetable scraps in a food processor and pulsing them with fresh aromatics, like garlic, ginger, or bay leaves. Then, cook it in water and strain.