There are two ways to go about making canned vegetables taste less metallic: try to extract the taste or cover it up. There aren't many ways to take the taste out, but plenty of seasonings stand a chance of making your vegetables taste better.
Before you can try to extract the canned taste from your vegetables, you should know what process you're trying to undo. Canned vegetables get that taste from being soaked in a can of "brine or liquid," precooked and then sealed, according to the Department of Agriculture. The containers then are cooked again to ensure that they preserve the food without refrigeration. Sometimes the vegetables take on the metallic taste of the can.
Blanch Your Vegetables
One way to try to remove the canned taste of vegetables is to blanch them. Do this by sticking the veggies in boiling water and letting them sit for two minutes. Take them out and dump them immediately in a bowl of ice-cold water to stop them from cooking any further.
You also can try adding some seasonings to your veggies; the seasonings may not give them a perfect pre-can taste, but they will make you veggies a bit more palatable. Shake a little salt and pepper over them or sprinkle on some lemon pepper seasoning. Even a pinch of sugar can do the trick. For a deeper veggie flavor, drop a bouillon cube in the pan with your vegetables while they heat up or cook them in vegetable broth.
More Food Fresheners
Spritz a little lemon or lime juice on your vegetables right after they're cooked; it adds a fun burst of freshness to canned green beans, spinach and more. Drizzle a bit of olive oil over canned greens for a light dose of flavor or splash on some malt vinegar for a bit of a jolt.