Bruce Aidells wrote a nice little book called Flying Sausages, which has a number of great recipes, and which helped me have a sausage-making revelation: sausage is nothing but spiced meat... casings are optional! I've made this one before with 100% lean ground turkey from the store (Jennie-O), was very good. You may need to add more spice to taste; I think I added more paprika and garlic to the original recipe (listed below).
Makes 7 to 8 half-pound packages
2 c. sliced onions (probably 1 large onion)
3 lbs. ground turkey OR 1.5/1.5 ground chicken/turkey (ground thighs are best), very cold or slightly frozen
1/2 lb bacon, cut into pieces, very cold or slightly frozen
1.5 tbsp garlic, chopped
1/4 cup paprika (smoked or regular)
2 tsp dried thyme
2 tsp yellow mustard seed
1 tsp dried sage
1 tsp dried oregano
1 tsp red pepper flakes
1 tsp cayenne pepper
1 tsp English-style dry mustard
1 tsp sugar
1/2 tsp ground allspice
4 tsp kosher salt
1 tbsp fresh ground black pepper
Simmer onions in water to cover until translucent, 5-7 min. Cool under cold running water & drain (this can be done ahead of time). Cool completely. Coarsely grind onions, meat, and bacon in a food processor in batches (using knife blade).
Add remaining ingredients to a big bowl, and mix thoroughly with your hands. Test fry a small piece in some oil, and taste for salt, pepper and other seasonings.
Divide into 7-8 portions, wrap tightly twice in plastic wrap or aluminum, and refrigerate or freeze.