I think the main rule of thumb is to just never, ever, ever boil/steam veggies and assume you end up with something anyone would want to eat. Roasting or frying them with liberal seasoning and/or flavorful oils ends up delish. You can also try frying carrots/broccoli/spinach or peas very quickly at a high heat and making a thick emulsified sauce from stock and butter that clings to it. Bear in mind cooking times, you don’t want to ruin the vegetables (or god forbid) peas by fully cooking them. As a result you might want to make the sauce first and then drop in more fragile veggies in later.