Put olive oil in large saucepan and heat on medium.
Add thinly sliced red onion and rosemary and cook, stirring occasionally, until onions caramelize and turn a deep golden brown.
Add sliced mushrooms and cook until soft and brown.
Add barley and cook and stir for about one minute.
Add marjoram and vegetable broth. Cover saucepan with a lid and simmer until barley absorbs most of the liquid and becomes tender, about ten to fifteen minutes.
Remove lid, stir in chopped spinach and stir until wilted, one or two minutes.
While spinach is wilting cut grape tomatoes into quarters.
Add quartered tomatoes and almond slices to saucepan and stir through until warm.