Vegetarian Seven-Layer Tostadas

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light sour cream

 (or use your favorite Taco Seasoning)

finely grated low-fat cheese such as Four Cheese Mexican Blend (or more if you like a lot of cheese)

chopped tomatoes

thinly sliced green onions

sliced black olives (or use a 4 oz. can sliced olives)

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olive oil for greasing baking sheet, about