Add the water, oats, sugar, salt, and cardamom to a medium saucepan over high heat and bring to a boil.
While the pan is coming to a boil, bring a cast-iron skillet to high heat. Toss in the nuts and stir around for half-a-minute to lightly toast. Immediately dump the nuts onto a cutting board, cool for a minute, and then chop.
As soon as the oats are boiling, reduce heat to medium-low, add the fruit and half of the toasted nuts, and simmer uncovered for ten minutes, or until the oatmeal is thickened.
Ladle the cooked oats into bowls and top with the rest of the toasted nuts, a drizzle of maple syrup, a sprinkle of cinnamon, and an optional glug of milk, if you happen to have it.