There is a cooking daily in Northrend. It can be one of five different quests.
Cheese for Glowergold
Convention at the Legerdemain
Infused Mushroom Meatloaf
To level your cooking you MUST do the dailies.
Three of the Dalaran Cooking Awards will allow you to buy recipes beyond 400 cooking. After three days you are guaranteed to be able to buy at least one recipe. Not all the recipes are relevant to your class so don’t get daunted by the number of cooking rewards you need to get them all.
You need to complete the cooking dailies to obtain Dalaran Cooking Awards. You receive at least one Dalaran Cooking Award plus a Small Spice Bag when you turn in the daily.
The Small Spice Bag also gives you Northern Spices. They also have a chance to contain a cooking award, but not likely. Ten Northern Spices can also be bought with one Dalaran Cooking Award. If you have a second toon that can cook have them do the cooking daily occasionally also. They can provide the spices you will need. I have yet to see the need to buy Northern Spices with Dalaran Cooking Awards.
For Mustard Dogs!, Rhino Meat can be pre-farmed. I have also been placing up on auction house stacks of four Rhino Meat and/or Rhino Dog. Rhino meat, leather, green drops, and grays make for a very profitable farming session.
For Sewer Stew, Crystalsong Carrots look like Golden Sansam. They are located in Crystalsong Forest right outside where the portal takes you down. To gain access to Crystalsong Forest from Dalaran, at 70 you complete the quest Learning to Leave and Return: the Magical Way. Which is picked up from Archmage Celindra in Dalaran.
My cooking would be maxed out if I was not finding it so profitable. *grin*
Also see: Wrath cooking world drops for your mood.