Just measure everything into a bowl and mix it up well. Keep this on hand in an old spice shaker.
So it’s a lazy summer day around the house. First, sprinkle your slab of ribs liberally all over with rub. Let them sit while you continue preparations. (Indeed, you can season your ribs the night before, if you like.)
You’ll need some soaked wood chips. You can buy wood chips anywhere you buy charcoal, in apple, mesquite, hickory, and very possibly other varieties – I’ve even had some made from old Jack Daniel’s barrels! Any chips will do. Fill a big bowl or old coffee can with chips and cover them with water. Sit them by your grill. You’ll also need a big square of heavy-duty aluminum foil; you’ll be putting your soaked chips on this.
Put a drip pan – disposable aluminum is perfect – under the grate on one side of your propane grill. (I’ll give instructions for charcoal in a bit, but I’m telling you, slow-smoking is the whole reason I broke down and got a propane grill.) Light only the burner on the other side. You’ll need to know the temperature of your grill. If your grill lacks a thermometer, you can pick up an oven thermometer in the housewares aisle of any grocery store. Put the thermometer in the grill, close it, and let it heat – you want it somewhere between 250-300F (120-150C).
While the grill is heating, go make your mop. Combine about ¼ cup of the same rub you used on the ribs, 1 cup of chicken broth or light beer, and about ⅓ cup olive oil. This is what you will use to baste your ribs.
When your grill is up to temperature, lay your seasoned ribs over the drip pan, on the side away from the lit burner. Put the square of foil over the lit burner, and put a big handful of those wet chips on the foil. Close the lid of the grill. Leave the vents open just enough to allow the fire to burn.
Go do something else for half an hour, while smoke pours out of the grill.
When the half-hour is up, grab your mop, a basting brush, and tongs. Go open your grill – check the temperature while you’re at it. Mop your ribs liberally with the mopping sauce, and use the tongs to turn them over end-to-end – this ensures even cooking. Baste the other side, too! Put another handful of chips on your foil, then close the grill again.
Let ‘em smoke another half-hour, then repeat the whole shebang: mop, turn, add chips, close the grill up again. You’re going to keep doing this every half-hour or so for 5-6 hours, or possibly a bit more, depending on the thickness of your slab and the weather. Yes, the weather – cool or windy weather can make it difficult to keep your grill up to temperature, while hot, sunny, still weather may make it over-heat a bit. Do monitor the thermometer when you’re mopping and turning your ribs and adjust the burner accordingly.
When the meat has pulled back from the bones at the ends, and the ribs are so tender you have to be careful turning them for fear of tearing them, they’re done. If you really want a finishing sauce, this is the time to put it on. Slather both sides and close the grill again, just for 10 minutes. But try these without sauce; they’re mighty good as-is!
Cut into individual ribs; I like to use my kitchen shears for this.