100 Montaditos is a Spanish chain of fast-food. In Spain, they have recently begun to offer gluten-free options in collaboration with the Spanish Association of celiacs (FACE).
The product they offer is good, but unfortunately, I had a terrible experience at one of their restaurants in Madrid, due to the total lack of staff’s preparation, which I will explain in detail below.
100 Montaditos gluten-free in Spain

This chain has many places in Madrid, concentrated mainly in the center. I was in the following (near the Gran Via):
Address: Calle de la Montera, 34, 28013 Madrid – Phone: 902 19 74 94
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They sell small sandwiches (about 2 bites) with many types of fillings and various types of beer.

They have 5 different gluten-free sandwiches, chips and the Cruzcampo beer.

The sandwiches are all sealed individually with the filling, heated and served still closed in their wrap, so there is no problem with cross contamination.

The potato chips, though gluten-free, didn’t give me any security, especially in the restaurant where I was. The sandwiches are very good either as bread than as filling.
Gluten-free sandwiches cost from € 1 to € 1.20 per one, while gluten-free ones € 3.50.

And now my disastrous experience in Madrid’s restaurant in Calle de la Montera: we ordered two sandwiches and chips, specifying well to be celiac and asking gluten-free sandwiches. They gave us the following sandwiches:

I wasn’t convinced by their look, they were ready in too little time and served by the same person who ran the “regular bread”.
We ordered 3 others, as they are very small, without having tasted the previous ones and we asked for more confirmation, both to the cashier and to the person who served us, that the sandwiches were actually gluten-free. They repeated to us that they were, that those numbers (each filling corresponds to a number) were gluten-free sandwiches. I tasted a sandwich and by the taste, I was less and less convinced. When we picked up the others sandwiches, we had again confirmation that they were gluten-free so I finished the first sandwich … just in time to see the waitress coming to us to tell us that they had given us all normal sandwiches!
The waitress blamed the cashier who was new at the job, because everything should start from the receipt, but even the people at the counter preparing the sandwiches don’t have the slightest idea of what a gluten-free sandwich means, because we asked them many times, so the problem is a total lack of staff’s preparation.
Gluten-free sandwiches are sealed, prepared elsewhere and come completely closed so they are safe; the potato chips are instead made in place and, considering the preparation of the staff, don’t eat them!
They have just begun to serve gluten-free products, so I hope they are going to improve the situation, meanwhile, I wrote both to the Spanish Association and to the central firm, what happened to me.

More gluten-free fast-foods in Spain: