Classic Beef Lasagna

Finely chop the onion.
Heat some vegetable oil in a large pan over medium heat.
Add the chopped onion and sauté until translucent.
Mince the garlic cloves and add to the pan, cooking until fragrant.
Add the minced meat to the pan and cook until browned.
Chop the celery stalks and tomatoes, then add them to the pan.
Season with salt, ground black pepper, and dried ground sweet paprika to taste.
Stir in the tomato sauce and let the mixture simmer for about 10-15 minutes until thickened.
Prepare the Béchamel Sauce: