As I understand it, the *reactive* surfaces to avoid are cast-iron, copper and aluminum.

So a high-end stainless steel (such as All-Clad) or an enameled cast iron (such as Le Creuset) is the way to go when cooking with anything overly acidic like tomatoes.

some aluminum, such as calphelon, is meant to be non-reactive. It's annodized and I've used it for years with success.

Ferrous metal can also alter flavors unless they have an enamel coating. Acids will react with iron pans.

Clay, enamel, glass, or stainless steel. These materials don't react chemically with food. (Aluminum & copper can react, changing the taste & color).