Chicken Tostadas and Avocado Dressing

I made this last night for some friends and I think it was a hit. It was super easy so I will definitely be making this again. I got this recipe from Cooking Light September 2011 edition.

Ingredients:
2 Tbsp sour cream
2 Tbsp chicken broth
2 Tbsp lemon juice
2 tsp canola oil
1/4 tsp ground red pepper
1/8 tsp salt
1/2 ripe peeled avocado
1 1/2 Tbsp canola oil, divided
4 (6 inch) flour tortillas
2 garlic cloves, minced
2 cups shredded chicken
1/2 cup shredded iceberg lettuce
1/2 cup chopped tomato
1/4 cup crumbled queso fresco

Combine first 7 ingredients in food processor until smooth. Cook tortillas one at a time in a nonstick skillet over medium heat. Cook for about 2 minutes on each side (or golden brown) in 3/4 tsp oil. Repeat with remaining tortillas. Add remaining oil to pan and add garlic and jalapeno; saute 1 1/2 minutes. Add chicken and cook another 2 minutes. Build tostado: tortilla, 1/2 cup chicken mixture, lettuce, tomato, cheese, and top with about 3 Tbsp dressing.