In a blender, combine basil, cheese, and lemon juice.
With blender whirling on lowest speed, slowly pour in oil to make a creamy-smooth mixture.
Place mushrooms in a bowl.
Coarsely chop pimento (reserve a few strips for garnish); add to mushrooms with rice, green pepper, and chili.
Pour over dressing, toss gently; add salt to taste.
Cover and chill.