This is my almost regular as clockwork Saturday night supper. I find it enormously easy and relaxing to make since all I do is go downstairs, put everything in the oven, and then go back up to Saturday evening tv in bed until it's ready - and then, frankly, back again.
If I cook the poussins/ Cornish hens in the same pan as the sweet potatoes, I cut a couple of slices of bread and put 1 underneath each bird in the tin, so as to absorb the juices and stop them from seeping into the sweet potatoes which, in turn, would prevent them from crisping and browning. But more often than not, I dispense with the bread (you can imagine how good it tastes later though) and just get 2 disposable foil roasting trays about the size of brownie tins each and put the poussins/ Cornish hens in one and the sweet potatoes in another and reuinite on the plate with a little watercress and a squirt of lime juice later. I must have English mustard with. I know it's a weakness, but not one I'm willing to renounce.
Preheat the oven to 425 degrees F. Put the birds into a small baking tin or foil tray pouring over 1 tablespoon of oil.
Cut the unpeeled sweet potatoes into 2 1/2-inch cubes and put them into another smallish tin or foil tray.Pour over the other tablespoon of oil and sprinkle over the spices, and then toss everything together by shaking the tin.
Cook both the poussins/hens and sweet potatoes in the preheated hot oven for 45 minutes.
Put each poussin/Cornish hen on a plate, with a tangle of watercress and the sweet potatoes alongside. Sprinkle with Maldon/kosher salt, to taste, and spritz with lime juice and go to it!