Cribbed from here and adjusted/adapted
Heat oven to 475 degrees. Place
2 Jalapenos
in a roasting pan, brushed with oil, and roast 6 min until soft. Remove the stems and some or all of the seeds and membranes, depending on how hot the peppers are and how hot you want the gravy. Dice the jalapeños.
Mix together
2t salt
1 T black pepper
1.5t garlic powder
1.5t onion powder
Rub
a pork tenderloin
with the spice mixture, rubbing it lightly so it adheres. Place this on a rack set in a roasting pan and sprinkle the roast with any remaining spice mixture, patting it in place. Roast for 30 to 40 minutes or until the pork reaches an internal temperature of 145 degrees (I prefer 150). If the fat begins to get too dark, tent with foil.
While roast is cooking, melt
3T butter
in a small saucepan set over medium heat. Add
4T + 2t flour
all at once and whisk vigorously until smooth. When the mixture thins and starts to bubble, reduce the heat to low. Cook for 1 to 2 minutes, whisking slowly, until the mixture smells nutty and toasty and is still light colored. Cook for 2 more minutes, stirring occasionally, then set aside and let cool.
Place
1c half-and-half
2c pork or chicken stock
1t salt
jalapeños
in a medium saucepan and bring to a boil. Quickly reduce heat to medium. Cook for about 5 minutes, stirring occasionally, until slightly reduced. Stir in 4 tablespoons of
the roux
and simmer for 2 to 3 minutes, whisking continually, until the sauce is thickened and bubbly. Stir in a little more roux if needed to reach the desired thickness.
When the roast is done, cover and let it rest for at least 10 minutes. Pour any accumulated juices into the gravy.
When roast has rested 10 min, Slice, cover in gravy, and serve.