Coat a large saute pan with olive oil. Toss in the smashed garlic and crushed red pepper and bring the pan to a medium heat. When the garlic becomes golden brown and very aromatic, remove it from the pan and discard it. It has fulfilled its garlic destiny. Add the onions, fennel and Swiss chard stems, stir to coat with the oil and season with salt, to taste. Stir in the white wine and the lemon zest and juice. Cover and cook over medium heat until the veggies have become soft and wilted but still maintain some texture, about 5 to 6 minutes. Remove the lid and cook until most of the liquid has reduced, another 3 to 4 minutes. Toss in the Swiss chard leaves, stir to combine and season with salt, to taste. When the leaves have wilted but still look vibrantly green, taste for seasoning. Reseason if needed (it probably will). Transfer to a serving bowl and serve immediately.