Oops! So sorry I never saw your reply! Hopefully by now you've figured out that all of the broth comes from the shellfish plus some fat from the kielbasa. Friends have tried adding wine or various herbs and spices, and it's fine, but I really prefer the natural taste of these ingredients cooked together like this. And it's just so easy. If you haven't tried making this yet, I highly re-recommend it. It's probably pretty easy to make a scaled down version too, since this recipe can be really expensive, but I only do it once every couple of years so I like to go all out. Made it a month ago and fell in love all over again.
Indoor Clambake. Hands down.
You have to join to view it on their website, but it's so easy you don't need their specific recipe. Here's my version for a crowd:
(Layered in a 16qt stock pot, from bottom to top:)
Cover and cook on stovetop over medium high for 30 - 40 minutes. Potatoes will take the longest, so check their doneness by threading a skewer down between the lobsters and corn. Done potatoes = done dish.
Take apart the lobsters and arrange on a large platter, cracking open the main pieces to make it easy on your diners. Divide other ingredients into several serving dishes and spread everything out family style on the table with flavored melted butters (orange, ginger, bleu cheese are favorites), lemon halves, shell bowls, sour cream (for the potatoes), etc. Makes a great presentation, and I love when I get to use all my fun and quirky serving vessels! It also makes a big mess so be prepared.
No seasonings, herbs, or liquid necessary. The shellfish give everything a briny perfume. It produces a lot of broth so serve that up too, with crusty bread.
Note: While the resultant broth prevents the kielbasa slices from burning on the bottom, they have left little circular impressions on the bottom of some stainless steel stock pots I've used over the years. I have been able to remove these by scrubbing with a scrubbing pad or wire brush (held with tongs) while boiling an inch of water in the pot.