As always when you want to make a historically accurate outfit, research is the first thing to do. I am going for a 14th century type of tunic, with narrow sleeves and flared front and sides. Some pictures I found are from the first half of the 1400s.
Fra Angelico - Dominicains 1420.
We can see here the narrow sleeves and also the collar of the tunic.
Bartolomé de las Casas - Anonyme 1566.
Bartolomé de las Casas - Anonyme 1566.
Another exemple of narrow sleeves.
Saint Dominic detail of la Pala di Perugia - Fra Angelico 1437.
Retable de Fiesole - Fra Angelico et Lorenzo di Credi 1420-1501.
I decided to go simple fabric wise, since he will be a monk I chose white cotton for the tunic, black and white cotton piqué for the hooden cloak (black wool would have been better but believe it or not it is impossible during summer to find woolen fabric in France).
I will be using the Reconstructing History RH014 pattern for the tunic, I think it will work pretty well!
Until next time !