opening restaurant in Brussel
If you need to ask that on a forum like this, maybe it is not a good idea.
You need premises in a good location with the right permissions to open a restaurant.
You need to set up a company - you will need to be qualified to set up as a restauranteur to do this. For example, if you are a bricklayer, you can not set up a chocolate business in Belgium. You need to have the skills and a certificate to prove it, or have several years of running a restaurant as a manager.
Good chefs - also qualified.
Meet all health and safety standards.
Loads of money to pay for the promotion, kitchen equipment, decoration, seating etc and enough money to keep you going until you start getting regular business.
That is just for starters - you are also competing in a flooded market where high quality food and service is expected.
Just give me €500,000 and save yourself 3 years of stress.