Step 1

In a large bowl, mix together the onion, broth, uncooked rice, parsley, egg, tomato sauce, olive oil, melted butter, mint, salt and pepper. Use your hands to crumble the beef over the top, then mix lightly but thoroughly.

Step 2

Pat the grape leaves dry with paper towels. Line the bottom of a Dutch oven with eight of the leaves. Place about 1 tablespoon beef mixture on the center of each remaining grape leaf, shiny side down, toward the stem end. Fold in the long sides of the leaf over the filling and toward the center, then roll up from the bottom. Arrange assembled dolmades, seam side down, on the grape leaves in the Dutch oven.

Step 3

Place a heavy plate directly on top of the dolmades. Add enough water to the Dutch oven to just cover the plate. Bring the liquid to a boil, then reduce the heat. Cover and cook until the rice is tender, 45 to 50 minutes.

Step 4

Meanwhile, make the avgolemono sauce. In a small saucepan, bring the broth to a boil. Reduce heat to a simmer. Finely grate zest from lemons into a small bowl. Cut the zested lemons in half crosswise, and squeeze the lemon juice into bowl with zest. Whisk in the eggs, salt and pepper until blended. Gradually add the egg mixture to the broth in the saucepan, going slow and whisking constantly as not to curdle the egg. Cook and stir over low heat until slightly thickened, four to five minutes, making sure not to boil. Editor's Tip: If you still have a bit of time before the dolmades are done cooking, you can keep the sauce warm over low heat, covered, until ready to serve. You could also wait until the dolmades are ready to serve before you start cooking this sauce, if you'd prefer!

Step 5

Uncover the Dutch oven, and remove the plate. Remove the dolmades using tongs, and drain the excess liquid. Serve with the avgolemono sauce. Editor's Tip: If you like, you can let the cooked dolmades cool for 30 minutes or so before you serve them. This will give time for the rice filling to set, letting the dolmades firm up a bit for a satisfying bite.