NY Times Lamb Sausage with Grilled Onions

I made this a few weekends ago and it was a huge success. I love lamb, and the sausages have such great flavor. With fresh lettuce, grilled onions, good tomatoes, and the spice dressing all topped with cilantro, it's an excellent summer dinner. It was supposed to have zucchini, too, but I totally forgot to buy zukes. Turned out great anyway!

Ingredients: 
For sausage

3 pounds ground lamb, or a mixture of half lamb and half beef or veal

2 teaspoons toasted cumin seeds

2 teaspoons toasted coriander seeds

1 teaspoon black peppercorns

6 allspice berries

2 teaspoons salt, more as needed

1/2 teaspoon cayenne

Pinch cinnamon

4 tablespoons mild paprika

8 large garlic cloves, smashed to a paste