Pat the cubes of beef dry with a paper towel and sprinkle all sides with salt and pepper; Dip them into flour to coat, remove excess flour.
In a heavy four quart casserole, heat the oil over high heat and brown the beef in the oil, turning them them evenly brown, transfer meat to plate.
In the same pan, add onions and saute 5 minutes until soft but not brown; pour in water or stock and bring to a boil over high heat while scraping the browned particles clinging to the sides and bottom of the pan; add beef cubes and bay leaf, reduce heat, simmer partially covered for 1 hour: then add potatoes, carrots and peas; partially cover the pan again and simmer 20 to 30 minutes longer, or until vegetables are tender.
As beef and vegetables simmer, check the pan from time to time; if liquid seems to be cooking away, reduce heat and add a little more water; When all is tender, remove from heat and let cool uncovered to room temperature.
For crust: In a food processor with fitted metal blade, combine flour, cornmeal, baking powder and salt; process just to mix; Add butter and process in short burst, scraping down sides of bowl if necessary, until the mixture resembles coarse bread crumbs.
Add the whole egg, egg yolk and 1 tablespoon ice water and process for a few short burst, scraping down sides until dough comes together but still crumbly; If dough seems to dry, sprinkle with up to one more tablespoon water; DO NOT overprocess or the crust will be tough.
Turn dough out onto a floured surface and work together into a ball the consistency of play-doh, Press down into a round disk and wrap with plastic, put in refrigerator for 1 hour.
Roll dough to fit the casserole that has the meat veggie mixture in; Place dough over mixture and bake in 350°F oven until crust is brown and stew is bubbling, Serve.