1TO PREPARE THE SAUCE:
In a large saucepan over medium heat, combine the tomatoes with chilies, tomatoe sauce, cilantro, chipotles, adobo sauce, lime juice, and salt.
2Bring to a simmer, stirring. Reduce heat to medium-low and continue to gently cook for 15 minutes, stirring occasionally.
3TO PREPARE THE MEAT:
Place a ;arge skillet over medium-high heat and add oil. When the oil is hot, add onions. Cook and stir until the onions begin to soften, about 3 minutes. Add the garlic and jalapenos, stirring to incorporate. Cook and stir for an additional 2 to 3 minutes, until the onions are well browned and the garlic and jalapenos soften.
4Add meat and toss until heated through and well combined, about 2 minutes.
5Add 1 cup of the sauce to the beef mixture, tossing to coat.
6Remove the sauce from the heat and add the broth. Using an immersion or standard blender, puree the sauce until smooth, it should be thin. Ladle the sauce into 4 bowls for dipping. Be sure the bowls are large enough so the sauce dosen't slop out when the sandwich is dipped.
7TO ASSEMBLE THE SANDWICH:
Spread the smashed avocado on both sides of the roll. Pile the meat filling on the bottom halves of the sandwich buns, close, and cut each sandwich in half. Arrange each sandwich on a plate with the dipping sauce on the side.
Dip and enjoy!