In a medium bowl, toss oil and potatoes until well-coated. Evenly spread potatoes onto one of the foil-lined sheet pans.
Place in oven and bake for ~10-15 minutes, or until lightly golden, tender inside, and crisp outside.
Next, designate 3 dishes for breading fish — one flour, one toasted panko, one beaten egg. Incorporate seasonings into panko mixture.
Coat one piece of fish at a time in egg, then flour, then egg again, and finally toasted panko. Place breaded fish onto remaining foil-lined sheet pan in a single layer and place in oven. Bake for 10-12 minutes, flipping half-way through.
While the fish and chips bake, in a medium bowl, microwave peas until bright green and heated through (~4-5 minutes). Next, gently mash peas with a fork and set aside.
Divide fish, chips, peas, and lemon into 4 portions. Optionally serve over a bed of arugula.