I was listening to a health conference once and Robert Lustig and Dr. Mennela were talking about food acceptance and the preference for sweet food. It can take between 10 to 25 try for a child to accept a new food, but give a sweet tasting food and the cild will accept it straight away.
You have a very tiny window of opportunity between now and 18 months to shape his taste preference .
The savoury world of food is very wast, and is not limited to purees. You can prepare a soupy risotto, a soup with grated parmesan and a tiny bit of butter or oil for added flavour, roasted veggies instead of steamed ones which you will blend. Very often, the savoury foods for babies are not very tasty given the lack of salt. But adding fresh herbs, garlic, onions, braising the veggies a bit, adding real parmesan, a sprinkle of nutritional yeast.
Instead of steaming your veggies, try braising them in a bit of water, cooking them in a pan, at low heat until almost all the water has evaporated. Or roasted in the oven with garlic and rosemary.
Make a small stew, first put diced onion, diced carrot, diced celery in a small pot with a bit of olive oil, then other veggies, going in order of hardness, then add enough water to cover the veggies and let simmer. Finish with freshly cut coriander or parsley, blend or mash.
The debate spoon-finger is focused on the way to deliver food, not the type of food you eat. There are so many terrible fake foods targeted at babies that are nothing but junk food for babies. Those melty puffs or other corn and oil based crisps with some nutrition-void vegetable powder to be able to label them as veggie-chips.
Opt for taste and flavour. My fist paediatrician in France told me to never give something I wouldn't eat myself. So I prefer my cooked spinach with a bit of butter or sautéed with crushed garlic in a pan, I prefer oven roasted pumpkin than boiled one.
As long as you stay away from heavily processed food and go for a variety of taste, it will be fine. Don't drop everything and open the cupboard for bread, fruit or yoghurt the second he turns the head away. Distract him with a toy.
Whenever buying yoghurt , read the label and the amount of sugar in the nutritional facts. There are many to make a food sweet tasting, fruit puree, concentrated fruit, corn starch, milk solid and so on.
Look at the label of your peanut butter. So many have 10% sugar and 5 % oil. Buy 100% peanuts one. if yours is not. Consider that white toast is quite sweet tasting if you chew it for 10 seconds.
Bottom line, persevere, go and try every single veggie you can find in the supermarket, add flavours, and enjoy a plate at the same time your son is eating. He might get more interested in your plate than his.