In a large bowl, combine 2 tablespoons flour, sugar and 1/4 teaspoon of lemon zest. Add pears; gently toss to coat. Transfer to a greased 8-in. square baking dish.
In a small bowl, combine the oats, brown sugar, cardamom and remaining flour and lemon zest, Cut in butter until mixture resembles coarse crumbs. stir in almonds. Sprinkle over pears. Bake at 375° for 35-40 minutes or until pears are tender and topping is golden brown.
For lemon sauce, combine sugar and cornstarch in a small saucepan. Gradually stir in water until smooth. Bring to a boil over medium heat; cook and stir for 1 minute or until thickened. Remove from the heat. Stir a small amount of hot mixture into egg yolk; return all to pan, stirring constantly. Bring to a gentle boil over medium heat. Cook and stir 1 minute longer. Remove from the heat; stir in butter, lemon juice and peel. Serve with warm pear crisp.