Roast chicken, seasoned simply with salt, pepper, lemon juice, and herbs, is perhaps the epitome of effortless cooking. For six people, look for an organic or free-range oven roaster (5 to 7 pounds) or two smaller birds (3 to 4 pounds), knowing that either way you will have some leftovers. I started adding hot Italian sausages to roast chicken when I had to enlarge dinner for unexpected guests. They add such great flavor that they have now become a permanent part of my roast chicken recipe, even when there is plenty of chicken to go around. If Italian sausages aren’t your thing, try chorizo, kielbasa, or Cajun sausages. Lay the chicken and sausages on a bed of baby Yukon gold potatoes, the ones with pale yellow skin and creamy golden interiors, so that the potatoes absorb all the juices and flavor from the meat as they roast. I mix in …