Place salad oil, flour and garlic in a saucepan; simmer.
Add tomato sauce, water, salt, pepper, chili powder and oregano. Simmer.
Brown hamburger.
Fry tortillas lightly.
Dip each tortilla into tomato sauce.
Place hamburger in center of tortilla; roll up and secure with toothpick.
Place in large shallow pan.
Pour remaining sauce mixture over rolled tortillas.
Sprinkle green onions and olives over top; sprinkle grated cheese over all.
Heat at 350° until bubbly.