0 Mix 1 tablespoon of the butter with the cornstarch and set aside.
1 In a saucepan set over medium heat, melt the remaining 3 tablespoons butter. Add the garlic, and cook until the garlic begins to soften, 2 to 3 minutes.
2 Add the peas and ¼ teaspoon each of salt and pepper, and cook the peas until they turn bright green, about 1 minute.
3 Add the half-and half and cook until it bubbles in the center, about 30 seconds.
4 Add the cornstarch mixture and cook, stirring until the content of the pan thickens and the peas are tender.
5 Add the lemon zest, parsley and tarragon. Taste for salt and pepper, and adjust if necessary. Serve immediately.
