METHOD
1) For the crust, put the cubed butter, the flour, salt, and the sugar in the bowl of a food processor. Pulse the ingredients until the butter is the size of chickpeas. Add the cold water, slowly, through the feed tube and pulse until the dough comes together. Add more water, a teaspoon at a time if needed, until the dough comes together in a ball. Take it out of the food processor, form the dough into a disk, and wrap it in plastic wrap. Refrigerate for at least 1 hour.
2) Preheat the oven to 375. Take the dough out of the fridge, roll it 1/4 inch thick, and lay it gently into a 9-inch greased quiche pan. Press it into the bottom gently, then trim the overhanging dough. Prick the tart base all over with a fork, then refrigerate again for 30 minutes so the dough has the chance to rest and doesn't shrink when baking. When ready to bake, put a piece of parchment paper over the crust, and add pie weights or dried beans on top. Put the quiche pan into the oven and cook for 20 minutes. After 20 minutes, remove the pie weights and the parchment paper, and continue cooking the crust for 10 minutes more so it browns more.
3) After the 10 minutes are done, remove the quiche dish from the oven and turn the oven down to 350. Scatter the onion, garlic, jalapeno pepper, tomato and cilantro across the base of the crust. Add the shredded cheese on top. In a bowl, whisk the 4 eggs, the milk or heavy cream, the Mexico City Barbacoa spice, and the salt. Pour the eggs into the quiche dish and bake for 25 minutes, or until the eggs are set. Let cool a bit, then serve with an arugula, avocado and black bean salad.