Tomato paste

Tomato paste is tomatoes cooked down until thick, which concentrates the glutamate that makes a ripe tomato taste savory rather than just sweet. The single most useful habit on this list is frying a spoonful in the oil with the onions, stirring so it does not scorch, until it turns a shade darker, before any liquid goes in. It loses its tinny edge and turns rich and roasted. That move improves chili, lentil soup, braised short ribs, curries and pan sauces, not just pasta. Buy it in tubes if half-used cans tend to go moldy in your fridge.