Step 1

Preparation Place rack in upper third of oven; preheat to 425°F. If you see or feel dirt in leeks, rinse well, separating layers, then pat dry; otherwise, leave rounds intact.

Step 2

Heat 1 Tbsp. oil in a 10" cast-iron or other deep, heavy, ovenproof skillet over medium-high. Cook sausage, stirring occasionally, until browned, 5–7 minutes. Add garlic and cook until golden brown, about 2 minutes more. Using a slotted spoon, transfer sausage and garlic to a plate, reserving about 2 Tbsp. oil in pan.

Step 3

Return pan to low heat and add flour, 1 Tbsp. at a time, stirring to combine. Cook, stirring constantly, until mixture starts to smell toasty and is the color of peanut butter, about 5 minutes.

Step 4

Stir in stock 1/4-cupful at a time. Bring to a boil, then reduce heat to medium-low. Add carrots, potatoes, and leek and simmer until carrots and potatoes are just softened and liquid is reduced by half, 10–12 minutes. Add reserved sausage and garlic, peas, dill, 2 Tbsp. lemon juice, 3/4 tsp. salt, and 1/2 tsp. pepper and stir to combine.

Step 5

Remove from heat. Place pastry over skillet, tucking corners gently into sides; it won't completely cover pan. Whisk egg with 1 Tbsp. water (if not using, substitute 1 Tbsp. oil) in a small bowl and brush top of pastry. Cut four 1" slits in pastry to vent.

Step 6

Bake pot pie until pastry is beginning to brown and underside is cooked, 23–25 minutes. Let cool 10 minutes before serving.

Step 7

Meanwhile, whisk remaining 4 Tbsp. oil, 2 Tbsp. lemon juice, 1/2 tsp. salt, and 1/4 tsp. pepper in a large bowl. Add spinach, arugula, radishes, cilantro, parsley, and almonds and toss to combine.

Step 8

Divide pot pie among plates and serve salad alongside.

Step 9

Cooks' NoteAny brand frozen puff pastry works; the weight may vary, but either way, you'll have enough to work with.