One of the most significant barriers that I see people struggle with in order to implement a special diet is lack of general cooking and kitchen skills. Over the last few generations many people haven't learned these skills as they would have in the past. This is especially true for traditional cooking methods, such as fermenting foods and making broth, but is also true for more basic cooking methods as well. Below are links that demonstrate some of this information.
General
New York Times Cooking
NYT specific cooking techniques
Bon Appetit and on YouTube
America's Test Kitchen (and on on YouTube and and Kitchen Smarts)
The Culinary Institute of America
French Cooking Academy
Chowhound (how-tos and recipes)
Cooking hints and tips from What's Cooking America
A nice collection of diagrams and graphics to illustrate and teach cooking.
Learning to cook without recipes (teaches technique)
Kitchen Conundrums with Thomas Joseph
(collection of tips, how-tos, and demos about all sorts of cooking questions)
Missing an Ingredient? Here Are Substitutions You Can Use Instead
Making Pie Crusts and Pies
New York Times Cooking
NYT Guide to Making Rice
How to Make Soup
How to Make Beans
How to Grill
How to Make Burgers
How to Roast Chicken
How to Make Fried Chicken
How to Make Pizza
How to Make Yogurt
How to Make Sourdough Bread
Perfect Boiled Eggs (actually steamed)
How to Use an Instant Pot
How to Make Ice Cream
How to Make Pancakes
Kitchen Tools
Kitchen Care | Basics with Babish
(how to season cast iron, sharpen and hone a knife, maintain stainless steel pans, and maintain wooden cutting surfaces)
Basic Knife Skills
More advanced knife skills with Jacques Pepin
Knife maker Explains The Difference Between Chef's Knives | Epicurious
How to care for cast iron pans
The benefits of choosing enameled cast iron
How to sharpen a knife using a whetstone
How to use and season a mortar and pestle
How to clean a spice grinder (coffee grinder)
Common Ingredients
Which Salt to Use?- Kitchen Conundrums with Thomas Joseph
The Science of Salt: How it Impacts Your Cooking and How to Make Your Own
Difference Between Table Salt & Kosher Salt in RecipesScience: When to Add Salt During Cooking—and Why
A Peppercorn Primer
(important- pink peppercorns can cause cross-reactions in people with peanut allergy. Also, black peppercorns are high oxalate but the white ones are not)
Baking Powder vs. Baking Soda- Kitchen Conundrums with Thomas Joseph
The Easiest Way to Clean and Reuse Frying Oil
The Science of Garlic and How to Make the Best Garlic Bread
Preparing Fruits and Vegetables
Jamie Oliver's principles for superb salads
Tips and Tricks for Perfectly Crisp Salads- Kitchen Conundrums with Thomas Joseph
How to Slice Every Fruit
How to cut an onion by Cook's Illustrated
Learn How Now: How to Julienne Vegetables
Ultimate Guide to LEMONGRASS - Hot Thai Kitchen
Reference guide for spiralizing vegetables
Easy method for peeling garlic cloves
Roasted peppers
How to Roast Green Chiles at Home
How to make crispy (not soggy) latkes
How to Roast the Best Potatoes of Your Life
How to cut a spiral potato
Best Baked Potato
How to Stir Fry Any Vegetable - Three Basic Flavors and Recipes
Mario Batali's basic pasta sauce primer
Animal Products for Cooking
How to render fat (making lard and other cooking fats)
How to render tallow
Rendering lard in a pressure cooker/Instant Pot
Rendering lard in a crock pot
DIY Bacon
How to Make Cottage Bacon
Salt Pork
Make your own anchovy paste
How to make vegan bacon
How to quick-cure salmon
How to Brine Meat -- And Why You Should Bother
Roasting bone marrow
Broth and Soup Stocks
Ultimate Guide To Making Amazing Chicken Stock
How to Make Chicken Broth in an Instant Pot
Chicken broth and stock
Perpetual stock or broth
How to make dashi (fish and seaweed broth used in Japanese cooking)
How to make 3 different Chinese soup stocks
Dairy and Dairy Alternatives
How to make cultured butter
How to make clarified butter (ghee)
Making Dairy-Free and Vegan Butter Substitute (margarine?)
How to make nut milk
How to Make Clotted Cream
How to make creme fraiche (aka sour cream)
Making Whipped Cream Substitute from Chickpeas (Aquafaba)
Simple Farmer's Cheese
How to make "zucchini cheese" or another method here
Cooking Steak and Other Meats
Four ways to season steak
Steak | Basics with Babish
How to Grill Steak for Beginners | Food Network
Grilling Pork
How to cook the tastiest lamb chops with Curtis Stone
How to Truss a Chicken in 6 Easy Steps
Conquering the fear of cooking fish
How to make crunchy crackling on a pork roast
How to Carve a Turkey
Making an indoor "grill" for cooking Yakitori and Korean barbecue
Understanding the Cuts of Meat
How To Grill NYTimes
Steak Cuts Explained
How To Butcher An Entire Cow: Every Cut Of Meat Explained
How to Butcher an Entire Pig: Every Cut of Pork Explained
How to Butcher an Entire Lamb: Every Cut of Meat Explained
WATER GLASSING EGGS: PRESERVE YOUR EGGS FOR WINTER!What’s the Difference Between Medium, Large, Extra-Large, and Jumbo Eggs?How to store eggs without refrigeration (water glassing)
How to cook eggs
How to make soft-cooked eggs
How to make perfectly poached eggs
Another poached egg video
How to make steamed eggs
Perfect fried eggs
Making a basic omelette
Every Way to Cook an Egg (59 Methods) | Bon Appétit
Cooking Rice and Grains
Secrets of Making Perfect Steamed Rice
5 Ways to Use Brown, Red and Black Rice | Hot Thai Kitchen
Perfect Persian Rice
How to Make Soba Noodles (can be made from Buckwheat to be GF)
How to Make Buckwheat Soba Noodles
Beverages
Basic guide to roasting coffee in a popcorn popper
Basics of Making coffee several different ways
DIY Cold-Brew Coffee
Vietnamese Egg Coffee
Scandinavian Egg Coffee
How to make Cuban coffee
Making Authentic Turkish Coffee
Arabic Coffee
How to Make the PERFECT Cup of Tea
Ingredients for Baking and Desserts
Complete Visual Guide to 11 Different Kinds of Sugar
How to make whipped cream
How to temper chocolate
Dutch Process Cocoa Powder vs. Natural Cocoa Powder
The Trick to Making the Perfect Sorbet
Making sorbet or ice cream without an ice cream maker
How to frost a layer cake
How to make a Cotton Candy Machine at home from a blender
How to make cotton candy by hand (hand-pulling method used to make Chinese noodles)
How to Make Chocolate Hot Fudge Sauce From Scratch