Tortillas made with blue corn flour, soft tacos with ground beef, deep fried oyster puffs are just a small part of the cooking demonstrations that will take place at the Smithsonian's annual Festival of American Folklife on the Mall from Oct. 4 to 9.

Indians from New Mexico, Mexican Americans and women from Chesapeake Bay towns will participate. There will be Mexican food, catered by Enriqueta's for sale.

The festival will be open from 10 a.m. to 5 p.m. daily. For more information call 3816264.

If you have a special recipe featuring oysters and would like to enter a cooking contest, try the "Magic With Oysters" contest, now in its second year.

The cook-off will be held during Chesapeake Appreciation Days, Oct. 28-29, at Sandy Point State Park, near the Chesapeake Bay Bridge.

For information on the contest write to: CA Days Oyster Cooking Contest, c/o Suburban Trust, 2083 West St., Annapolis, Md. 21401.

World Vegetarian Day, Oct. 1, will be celebrated at a conference on the campus of American University Sept. 30 and Oct. 1.

The conference is sponsored by the North American Vegetarian Society. The cost of the weekend is $20 and it includes the programs, meals and a bus tour. For additional information call 379-9362.