6 tablespoons unsalted butter
2 onions, minced
4 slices caraway-rye bread, crusts removed, torn into pieces
3 ½ cups low-sodium beef broth
1 cup sour cream
2 large egg yolks
½ teaspoon ground allspice
¼ teaspoon ground nutmeg
½ teaspoon salt
½ teaspoon pepper
1 pound 90-percent lean ground beef
1 pound ground pork
½ cup all-purpose flour
2 tablespoons soy sauce
2 teaspoons minced fresh dill
A 1 1/4-inch ice-cream scoop makes it easy to form these cocktail-sized meatballs. If you are keeping the meatballs warm in step 4, do not fully cover the slow cooker or the sauce will break.
1. Adjust oven rack to middle position and heat oven to 475 degrees. Melt 1 tablespoon butter in large skillet over medium-high heat. Cook onions until softened, about 8 minutes; transfer to large bowl. Add bread, 1/4 cup broth, 1/4 cup sour cream, yolks, allspice, nutmeg, salt, and pepper to bowl with onions and mash with fork until smooth. Add beef and pork and knead with hands until well combined.
2. Form mixture into 1 1/4-inch meatballs (you should have about 60 meatballs) and arrange on wire rack set inside rimmed baking sheet. Bake until lightly browned, about 15 minutes. Transfer to slow cooker.
3. Melt remaining butter in large skillet over medium heat. Whisk in flour and cook until beginning to brown, about 3 minutes. Slowly whisk in remaining broth, bring to boil, and transfer to slow cooker. Cover and cook on low until meatballs are tender and sauce is slightly thickened, 4 to 5 hours.
4. Transfer 1/2 cup sauce from slow cooker to small bowl. Whisk in remaining sour cream, soy sauce, and dill; gently stir into slow cooker. Serve. (If desired, meatballs can be held in slow cooker on low, partially covered, for 1 to 2 hours. Stir meatballs occasionally, adding up to 2 tablespoons water as needed to thin sauce.)
5. Make Ahead: Meatballs and sauce can be prepared and refrigerated separately for up to 3 days. To finish, transfer meatballs to slow cooker. Microwave sauce on high power, stirring every 30 seconds, until heated through, about 3 minutes. Pour sauce over meatballs and heat with slow cooker on low until heated through.
6. Make It a Meal: These tiny meatballs can also be served as a main course. To turn the Swedish Meatballs into a main course, in step 2 simply roll the meat mixture into 2-inch meatballs (you should have about 35 meatballs) and proceed with the recipe as directed. When spooned over hot buttered egg noodles or steamed white rice, these larger meatballs will serve 6 to 8.