Made about 25 pounds of bratwurst from scratch yesterday. Here's the recipe I followed. You should use 1 part beef to 3 parts pork. I kept the fat content low, probably 10-12 percent but I didn't measure.
For 2lbs of ground meat
1) Fresh sage minced 1 tbsp.
2) Garlic minced 1 tbsp
3) Sea salt 2 tsp.
4) Black Pepper 1 tbsp.
5) 2 eggs
6) ½ cup powdered skim milk
7) ¼ cup water
8) Mustard powder ½ tsp.
9) Caraway seed ½ tsp.
I used a little less eggs, water, and powdered milk for my batch. I fried up a bit before casing and it was fantastic.
For 2lbs of ground meat
1) Fresh sage minced 1 tbsp.
2) Garlic minced 1 tbsp
3) Sea salt 2 tsp.
4) Black Pepper 1 tbsp.
5) 2 eggs
6) ½ cup powdered skim milk
7) ¼ cup water
8) Mustard powder ½ tsp.
9) Caraway seed ½ tsp.
I used a little less eggs, water, and powdered milk for my batch. I fried up a bit before casing and it was fantastic.