Heat oil in a skillet set over medium heat. Add spinach and cook, stirring frequently, until wilted. Remove from heat and let cool. Season with salt and pepper.
Dressing:
Combine all ingredients in a mixing bowl and whisk to mix. Season with salt and pepper.
Barley:
Heat oil over medium-low heat in a large heavy pot with a lid; add shallots and cook, stirring frequently, until lightly browned.
Add barley to pot and cook, stirring frequently, for 1 minute. Add stock to pot and bring to a boil; cover with lid, reduce heat to low and cook for about 40 minutes.
Remove from heat, drain any excess liquid, fluff with a fork and let cool.
Salad:
Combine spinach, barley, corn, cherries, pork and feta in a large bowl and stir to mix. Drizzle generously with dressing, stirring to evenly mix. Season with salt and pepper and serve immediately.