In a medium pan boil the tomatoes until tender. Let them cool for a while.
In the meantime heat up some olive oil in a deep skillet. Add chopped onion and sautee. Add chicken breast and let it fry for a couple of minutes. Add pumpkin blossom and mushrooms and season to taste. Cook for about 5 minutes and set apart.
Blend cooked tomatoes, garlic, sour cream and the other ¼ of the onion until all the ingredients have come together in a smooth sauce. Use some of the chicken broth if necessary.
Cook in a medium pan on medium high heat until it starts to boil. Add chicken broth as necessary, it doesn't have to be very runny, though. Reduce heat to low, season to taste and let simmer for 10 minutes.
To prepare the crepes whisk together flour, milk, olive oil and egg until smooth. The batter has to be watery
Heat up a crepe or a non-stick pan and rub a little bit of olive oil or butter on all the surface.
Hold the pan away from the fire and with a small ladder pour a little bit of the batter. Immediately swirl the pan so the batter coats the bottom of the pan. If there are holes use more batter to cover them. Return the pan to the heat.
The crepe will quickly cook and dry. Using a non-metal spatula or a fork loosen the sides of the crepe and turn it over pinching the edge between your fingers. It will only take about 30 seconds to finish cooking.
Fill each crepe with some of the chicken and pumpkin blossom filling. Roll them and place them on a large plate.
Pour some of the sauce on top of the crepes and top with crumbled queso fresco and enjoy!
Recipe by What's Cooking, Mexico? at http://whatscookingmexico.com/2010/10/15/pumpkin-blossom-and-chicken-crepes/