Learn how to cook the St. Louis Por Rib portions that you find at Costco. For this recipe I use a two part cooking method that starts in a low oven and finishes on the grill.
Trying the Ribs from Costco
Right now I am on a mission to cook all the different cuts of pork that are available at Costco. I haven't ventured much into their rib selection. I have to admit I love the idea of eating ribs, but I don't often like to have messy hands while I eat - I know I am a wuss in that area.
I choose the St. Louis rib portions as I liked that they were conveniently cut into pieces that would make it easier to serve to my family. While I love sous viding ribs when I make them, but I wanted to cook the whole package at once and reheat the leftovers when it would be hotter later in the week. Instead I went with a slow oven method followed by finishing them on the grill with some homemade barbeque sauce.
Over on my Costnivore page, a Substack page dedicated to buying and eating meat from Costco, I am doing a $100 challenge to see how I use $100 worth of meat from Costco. These ribs are part of that challenge.
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Costco St. Louis Pork Portions
If you have never had St. Louis spare ribs before, they are ribs that have been trimmed down to remove cartilage. They are uniform in shape and I find them very easy to work with. You get a lot of good meaty pieces without too much work or fuss.
Costco is a great place to find them at. I find the quality of ribs to be top notch. The portions were cut into a size that is perfect for each person to have 1-2 portions depending on their appetitive.
The last time I purchased Costco St. Louis St. Louis Pork Ribs they were going for $3.79/lb in July 2025. The package was around 7 lbs. For an updated price and to see what other types of pork you can buy at Costco, check out my Costco Pork Guide.
Spice Rub Ingredients
For this recipe I am employ a double seasoning method that begins with a dry rub and finishes with a homemade BBQ sauce. The dry rub goes on the pork while it's cooking in the oven and the BBQ sauce goes on the pork when you finish it on the grill.
Here is what I used for my dry rub for this recipe:
- 2 tablespoons kosher salt
- 1 tablespoon freshly cracker peppercorns
- 1 teaspoon garlic powder
- 1 teaspoon onion powder
- 1 teaspoon sweet paprika
- 1 teaspoon dried thyme
- 1 teaspoon sun-dried tomato powder - optional ingredient that I like to add for more Umami flavor.
This rub will go all over the ribs right before you put them in the oven. This was enough for the nearly 7 pounds I had.
Barbeque Sauce Ingredients
I have posted a couple other recipes - Juicy Grilled Boneless BBQ Pork Chops and
Quick BBQ Chicken Skewers Without Marinade - this summer using this same barbeque sauce but I wanted to share it again with you for those that may have missed it.
- Ketchup – Use whatever store-bought ketchup you like. I typically go with whatever’s the best deal—especially with a family of six!
- Mild Vinegar – No balsamic here. You want something on the mild side, like white vinegar, rice wine vinegar, or apple cider vinegar.
- Molasses – This adds a rich sweetness to the barbecue sauce and deepens the color of the ketchup. If you don’t have any, you can substitute with brown sugar, which is just white sugar mixed with molasses - it will make the sauce sweeter.
- Garlic Powder – Use garlic powder, not garlic salt. Ketchup is already salty enough, so there’s no need to add more salt just to get that garlic flavor.
- Paprika – For this recipe, I use a combination of sweet and hot paprika. Smoked paprika also works great. I even wrote an entire post about how to find paprika that actually has flavor!
- Worcestershire Sauce – This is what brings the umami. Besides the ketchup, I’d say this is the most important ingredient. It adds a ton of complexity with just a little bit. Don’t skip it.
- Mustard Powder – This adds a subtle savory note. I don’t use enough to make it taste like mustard—it just makes the sauce taste better overall
The key thing to making the best BBQ sauce is to taste it when it's done and if you want more of an certain ingredient go ahead and add it. Make it your own.
Tips for Cooking the Ribs
Low and slow is the name of the game when starting these ribs. I begin by cooking them in a 275°F oven for about 2½ to 3 hours, or until they reach an internal temperature of 200-205°F.
At this point, the meat is tender enough to pull easily from the bone. You'll notice that the bones have become more prominent indication that the ribs have shrunk slightly as they cooked. Despite the tenderness, the ribs will still hold together well, making them perfect for finishing on the grill.
I cook the ribs in a heavy duty aluminum foil pouch that I put on a sheet pan. Seal it up tightly to get all the liquid since, but if it does get out you have the sheet pan to catch all that instead of the bottom of your oven.
When grilling, get your grill up to around 400-450 degrees. You are just trying to get some char on the ribs, since they are already fully cooked. I flip them around until I have charred each side, brushing on my homemade barbeque sauce as I go. Then they are perfect for serving with lots of napkins!
If you find yourself with leftovers, you can reheat them in the microwave and they will still be tasty.
Easy Costco St. Louis Ribs – Oven + Grill BBQ Recipe
Ingredients
- 6-8 lbs St. Louis Rib portions
For the dry rub
- 2 tbsp kosher salt
- 1 tbsp freshly cracked peppercorns
- 1 tsp sun-dried tomato powder optional
- 1 tsp garlic powder
- 1 tsp onion powder
- 1 tsp sweet paprika
- 1 tsp dried thyme
For the homemade BBQ sauce
- 2 cups ketchup
- 3 tbsp mild vinegar (apple cider or white vinegar)
- 4 tbsp molasses
- 1 ½ tsp garlic powder
- 1 ½ tsp sweet paprika
- ½ tsp hot paprika
- 1 tbsp Worcestershire Sauce
- 1 tsp mustard powder
Instructions
Starting the ribs in the oven
- Preheat the oven to 275 degrees.
- Combine all the ingredients for the dry rub into a bowl.
- Line a sheet pan with foil and place the rib on top of it. Make sure there is enough foil to make a pouch and completely cover the ribs.
- Pat the ribs dry with a paper towel before rub all the dry rub over all the pork.
- Seal the pork in the foil and place into the oven.
- Cook in the oven for 2 ½ to 3 hours or until the internal temperature of the pork is between 200-205 degrees and more of the bone is exposed.
- While the ribs are cooking, combine together all the ingredients for the BBQ sauce. Taste and adjust ingredients accordingly and then refrigerate the sauce until it's time to use.
Finishing on the grill
- Heat the grill up to around 400-450 or medium high.
- Remove the pork from the oven.
- Pour about ½ of the sauce into a bowl for brushing on the pork. Save the rest for serving.
- Place each pork rib portion directly on the grill grates. Brush with the BBQ sauce.
- Rotate the pork with tongs once you have marks on one side. Add more sauce and continue doing this until the pork is grilled all the way around. Remove to a clear sheet pan.
- Allow 5 to 10 minutes before serving. Serve with remaining BBQ sauce.
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