Prep the Veggies: Wash and dry all vegetables. Trim the zucchini, slice it into quarters lengthwise, and chop into 1/2-inch pieces. Core and seed the red bell peppers, then chop into 1-inch squares. String the snow peas by pulling the stem down the side, then cut them into thirds.
Heat the Pan: In a large skillet or wok, heat 1/2 tablespoon (30 ml / 1 fl oz) of butter and all of the oil over medium-high heat until the butter is shimmering.
Sauté the Vegetables: Add the zucchini and sauté for 2 minutes, stirring frequently.
Add the red peppers and cook for 3 more minutes, continuing to stir. The vegetables should be getting tender but still have a crunch.
Add the Glaze: Toss in the snow peas.
In a small bowl, quickly mix the tamari and lemon juice, then pour it over the vegetables.
Cook for 1-2 minutes, tossing constantly, until the snow peas are bright green and the glaze has been absorbed.
Finish with Butter: Remove the pan from the heat.
Add the remaining 1/2 tablespoon (30 ml / 1 fl oz) of butter, cut into small bits.
Stir until the butter is melted and coats the vegetables in a light, glossy sauce.
Serve immediately.