Seasoning steamed vegetables (in particular potatoes): advisable?
One thing we have found that helps in adding flavor during the steaming process is to slice garlic thinly, and line the bottom of the steamer basket with the garlic. Then afterwards, toss the garlic in with the potatoes and add salt/pepper/etc. (I'd probably add paprika, onion powder, and a pinch of cayenne.) 

I would imagine orange or lemon peel might work the same as garlic when steamed, although you might get better results tossing the steamed veggies with some zest. 

You can also toss the steamed potatoes with vinegar or lemon juice (whether or not it's combined with oil is up to you) along with the spices. 

Another option would be to bake your potatoes rather than steam them. Just wash, poke, and bake at 350F for 1 hour. There's no more fat, but the flavor and texture are VERY different. Just make sure not to wrap them in foil, since you won't get the same results. (Wrapping potatoes in foil is essentially steaming them, and the crust won't get crisp.)