Salsa ranchera (ranch sauce) contains tomatoes, chiles, onions, salt and usually a few other ingredients. The salsa goes by other names as well, even simply “salsa.”
 
 
Gourmet Sleuth
Salsa Ranchera (Ranch Sauce)
Use salsa ranchera for making huevos rancheros or use with shredded meats such as beef or pork for making tacos. Adapted from a recipe by Diana Kennedy.
Makes 1/2 cups
 
I N G R E D I E N T S
2 garlic cloves, peeled and chopped
2 pounds (about 4 large) fresh ripe tomatoes, roasted (instructions)
5 serrano chiles, roasted (instructions)
2 tablespoons vegetable oil (neutral flavor, safflower, canola)
2 rounded tablespoons finely chopped white onion
1/2 teaspoon salt (or to taste) preferably sea or Kosher salt
 
I N S T R U C T I O N S
Place garlic, tomatoes and chiles into a blender or food processor and blend to a slightly chunky (not smooth) sauce.
 
Heat the oil in a heavy frying pan and add the onion and cook until it becomes translucent, about 3 minutes. Add the blended ingredients and cook over high heat till reduced by half. Make sure to keep scraping the bottom of the pan.  There will be flecks of charred tomato and chile skin which is the way the sauce should be.
 
Cooks.com
RANCH SAUCE  
1/4 c. chopped onion
1/4 c. lard
2 c. chopped tomatoes
2 tsp. dry oregano leaves
1 tsp. salt
1/2 tsp. pepper
1/4 tsp. sugar
1/4 c. canned jalapenos
 
Saute onion and lard for 4 minutes add remaining ingredients and simmer 20 minutes. Serve hot with tortilla chips and cheese.
 
Google Books
The Food and Drink of Mexico
by George C. Booth
Los Angeles: Ward Ritchie Press
1964
Pg. 98:
Salsa Azteca (AZTEC SAUCE)
This is the basic sauce of Mexico even though it appears under half a dozen aliases. Its contents change as easily as the funds of an embezzled bank. This salsa is practically always found on the table (Pg. 99—ed.) in any home or restaurant. It is made fresh daily and is spooned into soup and over beans, meat and vegetables.
 
It is also called salsa ranchera and salsa Mexican. If you wish some, just say salsa, and it will show up.
 
In this primitive mash the ingredients are mixed in a stone mortar with a pestle; this is called a molcajete. If you have been softened by civilization, use a food chopper.
 
20 chiles verdes
20 large tomatoes
1 medium onion
5 cloves of garlic
1 tsp. fresh coriander
Wine glass vinegar
4 tsps. olive oil
Salt
 
Stem and seed chiles and put in chopper with tomatoes, onion, garlic and coriander. Stir in vinegar and oil and salt to taste. This sauce is soupy and the piquancy depends on the blender. This is more than a day’s supply if you are not a member of a large Mexican family, but will serve you and ten guests for a day to be remembered. Cut down accordingly.
     
18 August 1959, Frederick (MD) News, pg. 7, col. 6:
TOMORROW’S DINNER: Prairie chowder, frankfurts with ranch sauce (sweet pickle relish, brown sugar, tomato soup), baked beans, catsup, head lettuce salad, French dressing, Boston born bread, butter, fruit cup, oatmeal cookies, milk (coffee, tea).
 
3 September 1961, Long Beach (CA) Independent Press-Telegram, Cook Book, pg. 26:
HUEVOS RANCHEROS—CALIFORNIA STYLE
(...)
2 tblsp. Salsa Ranchera
   
23 June 1963, Long Beach (CA) Independent Press-Telegram, “How to Interpret Mexican Menus,” entertainment section, pg. 25:
SALSA VERDE—Green chili chopped with onion, tomato, oil, vinegar, salt, pepper. Served cold as relish, or heated with cheese.
SALSA RANCHERA—Salsa made with green chili.
(...)
VERDE—Green as in Salsa Verde or Ranchera green chili sauces.