It's about understanding flavors, how to build and combine them with good technique paramount.
Technique you're learning from recipes and discussion here and videos.
Understanding flavor comes from tasting. So you need to think about the food you're eating that you've cooked and that you eat elsewhere. What flavors can you discern? What techniques can identify in the creation of dish?
As you're cooking from a recipe, try to tell yourself why you're doing what you're doing. Heat a pan on medium heat. Why? Why that pan, why that size? And so on.
Taste your food at different points as you cook it. It helps to start with a simple flavoring and work forward.
Take a bit of chicken, cook it unseasoned and eat it. Now do it with a little salt. then salt and pepper. Compare each difference in your mind. How much salt can you add to the chicken with the flavor improving each time until it becomes too much? That level varies with how you're cooking the meat, what cut it is and what animal it comes from.
Now start adding other flavors to the dish, perhaps some thyme. Try adding thyme at the start, middle and end of cooking. Each will taste different as the flavors have time to combine, mellow or change, or be bright and strong as they remain when added late. Paul Prudhomme does this technique in many of his dishes. He'll add some of this spice mix at the start, middle and later in the cooking. He wants the accenting flavors to be present in as many forms as it will take on during the cooking of the dish.
As a counterpoint, Chinese Cuisine is built around contrasting flavors and textures in the dish so that things don't taste all alike (American Chinese Restaurants don't particularly exemplify this trait as they smother everything in strong sauces--that's not how they really cook).
So the meat will often be marinated in soy and rice wine, the vegetables hit with aromatics like ginger and garlic and perhaps seasoned with salt, a little sugar, white pepper. And a final glazing sauce built around fermented flavors from bean pastes, oyster sauce, and so on. So rather than blending things to a unified taste in the French/Westernized style, they build dishes and menus to more strongly contrast, achieving balance as a whole rather than in the one.
Indian cuisine can be quite baffling to deconstruct as there is such a medley of spices used in their cuisine. More so than any other cuisine IMHO, Indian food is best understood in the cooking of it. Blend your own garam masala and other spices rather than rely on stores and the internet.
Learning to taste so you can identify flavors and how they were built gives you the understanding of flavor to begin cooking things to your own taste profile, developing your own dishes as you go.
Pepin is certainly relying on an understanding of seasoning, technique and enough experience to have internalized the flavors profiles of particular dishes and how to achieve them.
Analyzing your own experience of eating, cooking and the steps along the way is how your build that level of experience and understanding.
