Patatas Bravas (Spanish Crispy Potatoes with Spicy Tomato Sauce)

For 2 servings, prepare 500 g potatoes, 3 tablespoons olive oil, 200 ml tomato puree, 2 garlic cloves, 1 teaspoon smoked paprika, 0.5 teaspoon chili flakes, 1 teaspoon salt, and 0.5 teaspoon sugar. Cut the potatoes into bite-size cubes and rinse them in cold water until the water becomes clearer. Drain in a colander, then dry every surface carefully with towels. Coat the pieces with most of the olive oil and part of the salt. Spread them in one layer on a tray preheated in a 210°C oven, leaving space between the cubes. Roast for 25 minutes and turn them halfway through so several sides become browned and firm. While the potatoes cook, warm the remaining oil in a pan over medium-low heat. Add the minced garlic and cook for about 30 seconds, stopping before it browns. Briefly stir in the smoked paprika and chili flakes to release their aroma. Add the tomato puree, sugar, and remaining salt. Simmer over low heat for 8 minutes, stirring until the sauce is thick, glossy, and no longer watery. Transfer the hot potatoes to a plate and spoon the warm sauce over them immediately. Serve at once while the roasted edges are still crisp.