I went 100% meat diet for 2 weeks then one-by-one slowly reintroduced different vegetable back into my diet until i figured out what made me bloated.

It's not an allergy, it's an inability to digest something you're eating. Gas is what happens when undigested food gets to your colon and the bacteria go to work on it.

I would suspect one of the following:
1: Fructose intolerance
2: Problems with FODMAPS generally

If you're being reasonably strict with your Paleo, I suspect 2 over 1. It's easy to test: drink a soda or some fruit juice. If you get gassy, it's 1. If not, it's most likely 2.

Onions and Brassicae (cabbages, artichokes, broccoli) are typical FODMAP culprits, but there are many more possibilities in the vegetable kingdom.

JS

broccoli, cauliflower, and brussel sprouts!

i found this on "drweil.com" by andrew weil, MD

Despite their healthy profile, some high-fiber cruciferous vegetables have bad reputations as gas producers due to their content of an indigestible sugar called raffinose (Larger amounts of raffinose are found in beans, which are notorious for inducing flatulence). Methane-producing bacteria in the colon feed on raffinose and release gas in the process. There's nothing you can do to broccoli and other crucifers to cut down on the gas they induce. Extra cooking just makes them unpalatable and destroys vitamin content (incidentally, cooking broccoli in aluminum or copper pots also destroys vitamins and ruins flavor). The extent to which your body produces gas depends on the types of bacteria in your colon that break down foods for digestion - we all are born with unique assortments of gut flora.

Broccoli and the other vegetables you mention are so good for you that it's worth making an effort to minimize their gas-producing effects so you can enjoy their health benefits. You can try eating yogurt, kefir, or buttermilk regularly, to boost the friendly bacteria in your colon. Taking probiotic supplements, like lactobacillus GG, might be an even better way to do this. Lemon juice with meals can also be helpful. And limiting high-fat foods can reduce bloating and discomfort and help the stomach to empty faster, allowing gases to move more readily into the small intestine. You can also try taking Beano before eating your broccoli. Available at health food stores, it is made from a plant-derived enzyme that breaks down raffinose before it enters the colon, thus reducing gas production.

In addition, you might experiment by eating very small amounts of broccoli every day, gradually increasing your intake to see if you can build up tolerance to it. Finally, fennel seeds can help expel gas from the digestive tract - try chewing and swallowing a half teaspoon at the end of a meal. Indian grocery stores sell sugarcoated fennel seeds as digestive aids

sounds like a food allergy of some kind for sure. You should probably do an elimination test and eliminate eggs, nuts, and any other suspected foods.

Did you use a salad dressing? What was in it? Anything else for dinner?

The only thing that gives me gas is gluten.

Could be intolerant to nightshades. What's in your big-ass salad? Are you eating high oxalate veggies raw like kale or spinach? Have you tried cutting the onion for a week or two and seen if it makes a difference?

it's never random. it's likely that something in the salad is causing it. probably a FODmap food, or another sensitivity.

In my experience, Either there is an intolerance to something you are eating, or you are eating hard-boiled eggs that have been overcooked.

Or, something "snuck in" to your food supply... like eating in a restaurant and not knowing something funky got digested.

I usually get gassy if eating onions and nuts

In my super high raw & cooked veggie warrior diet and paleo times I got it pretty often. Since I greatly reduced my vegetable intake my digestion is so much better, can't believe I was so stupid to think the more veggies the better. Nowdays I only get it if I eat (too) hard boiled eggs, no problem with soft boiled.

I rarely get bad gas now (I used to have terrible gas pains on a grain-heavy diet). But I have repeatedly gotten gas pain from jarred Indian sauces (think Tikka Masala or the like) I use sometimes to give a kick to my meat. I read the ingredients closely and there's nothing really bad in there (a little canola oil maybe), so I have to think it's something about the tomato/onions/garlic individually or in combination, though I haven't experienced major reactions (that I've noticed) from eating those foods in other contexts. I've had the effect with different brands, too. Very odd -- it's happened enough times that I know I'm not imagining it. Probably should lay off the sauce (!) but sometimes I crave that taste and there's no Indian restaurant in my town.

I would check for food intolerances/sensitivities: gluten, fructans/FODMAPS, Histamine intolerance.

Can undercooked eggs do that to you as well? Gas problem

Cabbage does it to me!