Remove and discard husks from tomatillos; rinse tomatillos well. Cut chilies in half lengthwise; remove and discard stems, seeds, and veins. Cut onion crosswise into 1-inch slices. Arrange tomatillos, chilies (cut sides down), onion, and garlic in a single layer in a 10- by 15-inch pan.
Broil 4 to 6 inches from heat until vegetables are well browned, 15 to 20 minutes. When garlic is cool, peel.
Transfer vegetables and any liquid to a blender or food processor. Add broth and cilantro; whirl until smooth.
Pour chili mixture into a 3- to 4-quart pan over medium heat; stir occasionally until steaming.
Meanwhile, in a 5- to 6-quart pan over high heat, bring 2 quarts water to a boil; add ravioli. Stir occasionally until pasta is tender to bite, 4 to 6 minutes; drain.
Add ravioli to the chili mixture and stir gently. Spoon equally into wide bowls. Garnish with tomato and add salt to taste.