Buying gluten-free sauces and condiments can be tricky — many of these products contain gluten ingredients. In other cases, products you wouldn't think to suspect, such as soy sauce, actually are made primarily of wheat.
Therefore, I urge a healthy dose of "buyer beware" when you're shopping for condiments and sauces. In some cases, you'll find products labeled "gluten-free," but in the majority of cases, you'll need to contact the manufacturer to determine if something is gluten-free or not.
You shouldn't have too much trouble finding a gluten-free tomato sauce to go with your gluten-free pasta; several brands, including Del Monte and Classico, offer options. In addition, Emeril's and Hidden Valley Ranch both offer gluten-free salad dressing products, although you need to check ingredients on each package to be certain you're choosing a safe flavor.
When it comes to ketchup, Heinz is considered gluten-free. French's yellow mustard is listed as gluten-free, as are many other mustards. If you need soy sauce, look for either Kikkoman or San-J tamari-style soy sauces, which are gluten-free at least to the FDA's proposed 20 parts per million standard, and will be marked as such.
There's one caution for those who are super-sensitive to gluten or who react to gluten-based vinegars (as I do): almost all of these condiment products contain vinegar of some sort. Some of it is apple cider vinegar, which should be safe enough for most people, but some of it may be grain vinegar — you'll need to check labels to be sure.
Gluten-Free Oils, Spices: Choose Fewest Ingredients
Most oils, including olive oil, corn oil, canola oil and other specialty oils, are considered gluten-free. However, it's possible to run across gluten in some specialty oils — I saw a gift-boxed flavored olive oil recently that contained gluten. Your best bet is to stick with plain oils, and flavor them yourself if you want variety.
That brings us to spices. Fresh herbs and spices you can purchase in the produce section of the grocery store are perfectly safe, as far as I can tell, and I use these exclusively when I'm not growing my own spices.
If you prefer to buy dried spices, McCormick's single ingredient spices are gluten-free to 20 parts per million, although McCormick's reportedly processes gluten-containing spices on the same equipment. You'd need to check for gluten cross-contamination in other manufacturers' spices, since many companies use gluten as an ingredient in some spice mixes.
Plain salt and pepper should be gluten-free, but watch out for those trendy flavored salts — a few contain gluten.