A delightful and hearty vegetable casserole topped with crispy potatoes, perfect for any occasion.
Preheat your oven to 400°F (200°C).
Preheating ensures even cooking right from the start.
Peel and slice the potatoes thinly, then set them aside.
Uniform slices ensure even cooking and a consistent texture.
Chop the carrots, celery, and onion into bite-sized pieces.
Keep the pieces similar in size for even cooking.
In a saucepan, heat a tablespoon of olive oil and sauté the onion and garlic until fragrant.
Stir frequently to prevent the garlic from burning.
Add the carrots and celery to the saucepan and cook for another 5 minutes.
Cover the pan to help the vegetables soften faster.
Mix the flour, tomato paste, mustard powder, and water in a bowl until smooth.
Whisk thoroughly to avoid lumps in the sauce.
Pour the sauce over the vegetables and bring to a simmer.
Stir constantly to prevent the sauce from sticking to the pan.
Transfer the vegetable mixture to a casserole dish.
Spread the mixture evenly for consistent baking.
Layer the potato slices on top of the vegetables, overlapping slightly.
Brush the potato slices with olive oil for a golden finish.
Bake in the preheated oven for 45 minutes until the potatoes are golden and crispy.
Check halfway through to ensure even browning.
Garnish with fresh parsley before serving.
Serve hot for the best flavor and texture.
