Melt 1 tbls. of butter with olive oil in a 10" saute pan over medium low heat. Add onions and 1/2 teaspoons salt. Cover and cook, stirring occasionally till onions are soft and translucent, about 5 minutes.
Uncover, raise heat to medium high and cook until onions are a light golden brown. Stir often, about another 3-4 minutes.
Add remaining 1 tbls. butter and zucchini. Cook another 3 minutes.
Add corn, garlic and 1/2 teaspoons salt. Cook, stirring frequently, scraping bottom of pan to get up the little bits, about 3-4 more minutes.
Add cumin, cook and stir another 30 seconds. Remove pan from heat.
Add all but 1/2 tbls. mint, basil, chives and parsley. Add a few grinds of fresh pepper, a good squeeze of lemon juice.
Stir, let sit for 2 minutes, stir again. Season to taste with more salt, pepper, and lemon juice.
Sprinkle remaining 1/2 tbls. mint over top.