what is the best way to gain weight?

You know, I tried for over a year not very successfully, until recently. I started working at a labor intensive job and I eat fruit all day long for fuel, plus a big green smoothie. I wake up very early and usually just have a green juice for breakfast and nothing more until my first break 5 hours later. Then when I get home in the evening I have a big supper of a salad with avocado and sprouted buckwheat. I didn’t intend to but I’ve been gaining quite a bit of weight. And I’m sure a lot of it is muscle as I’m getting much stronger.
Hope this helps.

Nuts, seeds, dates and dried fruit, honey, agave,. Plus the sweeter fruit, starchy veggies like winter squash, sweet potatoes, and parsnips. Avocados, and oils.

Thanks to all!!!