Add the potatoes to a large pot of boiling water; cook until tender, about 10 minutes. Coarsely mash; let cool.
Meanwhile, in a large nonstick skillet, heat the olive oil over medium. Add the cod; cook until flaky, about 4 minutes per side. Let cool.
In a large bowl, mix the potatoes, fish, milk, oats and eggs; season with salt and pepper. Form into 6 cakes. In a large cast-iron or nonstick skillet, heat the canola oil over medium. In 2 batches, cook the cakes until browned and heated through, 4 to 5 minutes per side.
In a large bowl, toss the spinach, apples, sliced strawberries, clementines and cranberries. In a small bowl, whisk the chopped strawberries, lemon juice, olive oil, honey and mustard; season.
Divide the salad and cod cakes among plates. Drizzle with the vinaigrette and garnish with the almonds.