In a 1-quart saucepan, whisk together the Campbell’s® Condensed Cream of Asparagus Soup and the milk. Heat to simmering, then hold at a low heat until ready for use.
Heat the vegetable oil in a 12” skillet. Fry the corn tortillas until they are golden brown, about 1 minute on each side. Remove the tortillas from the hot oil, and drain on paper towels.
In a separate 10-inch skillet, heat 2 tablespoons of vegetable oil. Add the onions and sauté for 1 minute. Add the mushrooms and bell peppers, and sauté for 2 minutes, until tender. Add the shrimp and sauté at a high heat for 2 minutes, until the shrimp are completely cooked (chicken, if substituted, should be sautéed until fully cooked, about 7 to 10 minutes). Salt and pepper to taste, then set aside.
Assemble your tostada by spreading a small amount of the Campbell’s® Cream of Asparagus soup on the fried tortilla, then placing a portion of the sautéed shrimp and vegetables on top. Garnish with sliced avocados and cilantro, and serve with any remaining Campbell’s® Cream of Asparagus soup as a side sauce.