Step 1

Preheat the oven to 400 F.

Step 2

Mix the condensed soup and water in a 9x13-inch casserole dish.

Step 3

Mix in the tuna, salt, pepper, and mustard.

Step 4

Break apart the frozen peas and stir them into the tuna mixture along the noodles, making sure to submerge the latter in liquid..

Step 5

Top the casserole with half of the dill fronds.

Step 6

Bake the casserole for 20 to 25 minutes, or until the noodles are soft and most of the water has been absorbed.

Step 7

Top the casserole with the crispy onions and bake it for another 5 to 10 minutes, until they are crispy and golden brown.

Step 8

Top the cooked casserole with the remaining dill.